Bumblebee Goby: Effective Maintenance and Breeding, and
Raising of Fry
John A. Lednicky, Ph.D.
Aquarticles
Introduction
Thirty-seven years prior, I had seen bumblebee gobies for the first time in a
Philippine shop that was part of a warren of room-sized pet stores in a bustling market.
Thirteen years old at the time, I had successfully bred numerous generations of
livebearers and egg-layers including angelfish, tiger barbs, neon tetras, and jewel fish (H.
bimaculatus). Nevertheless, the humble-looking elderly Filipino shop owner
recommended more fish-keeping experience before purchasing the gobies, claiming they were
a challenge to maintain. He said they required domestic "asin" (natural
sea-salt) in their water and would only eat "kiti-kiti" (mosquito larvae).
Interesting advice, considering the gobies were displayed in a homemade tank whose glass
sides were bound together with asphalt, aerated by a simple bubbler, the water
trickle-filtered through a suspended bath sponge. Rudimentary as the whole set-up looked,
the fish were yellow-green beauties with distinct dark vertical bands, and they were
furiously pursuing "kiti-kiti" in the display tank.
Fast forward to spring of 2003. Now an Illinois resident, I had established a 10-gallon
fresh-water aquarium for my young kids. Two months after it had been kick-started with two
guppies and the nitrogen-cycle and plants established, it was time for additional small
fish. While browsing at a local aquarium shop, my then three-year old son spotted
bumblebee gobies and asked if he could have them. Recalling what I had been told years
earlier, and not having researched the topic, I thought the gobies would be unsuitable for
our tank. However, one of the shop attendants informed us that the bumblebee gobies were
exceedingly popular, easy to keep, were tank-bred, raised solely in fresh-water, and were
'scavengers' that ate flake food. Furthermore, he assured us that none of his customers
had ever complained about any difficulties with the fish. "Buy them now", he
said, as experience showed that each new shipment of bumblebee gobies would be sold by the
following day. Hearing all that, and urged by my son, eight specimens were purchased. All
the bumblebee gobies in the store that day were notably small, lethargic, and with the
exception of one individual with a yellow body, all had narrow light black stripes and
whitish bodies. They did not look anywhere as attractive as the fish I remembered seeing
in the Philippine pet shop. I pondered whether I had remembered incorrectly. Also, had the
Filipino shop owner been so misinformed about these fish? According to the Illinois
salesman, the single yellow-bodied fish specimen in his store was 'probably' stressed, and
the shop's bumblebee gobies were tiny as they were juveniles from a recent hatching. He
recommended maintaining them at 75°F in neutral pH water, and proudly proclaimed that his
fish shop routinely added one tablespoon of aquarium salt (purified
sodium-chloride, not sea-salt) per 10 gallons of water, his tone as if he had revealed a
trade secret of major importance.
The gobies and four painted (red, green, pink, orange) Chanda glassfish (also
recommended by the same salesman) were placed in the heavily planted 10-gallon tank. Tank
and water parameters were: long-type tank with crushed coral bottom, outside power filter,
standard fluorescent lights, water temperature 75° F, one tablespoon of aquarium salt/10
gallons, pH 7.3). Dechlorinated, pre-aerated tap water with average calcium concentrations
of around 38 mg/liter was used. Plants were Java fern, and unspecified species of potted Cryptocoryne,
medium Vallisneria, potted medium Amazon sword plant, hairgrass, and Myriophyllum.
That evening, I viewed images of bumblebee gobies on the internet and realized our fish
looked overly slim and perhaps 'emaciated'. I also learned that painted glassfish usually
perished quickly. A foreshadow of things to come? Over the next two days, none of the new
fish were observed feeding on flake food. Three of the glassfish died. The single
remaining glassfish had developed white spots on its fins, body, and face. A phone call to
the pet shop the next morning was informative: the glassfish had been from a 'bad batch',
and would be replaced provided the sales receipt and dead fish were shown as evidence.
Disregarding advice from the pet shop about adding medications to the tank, I increased
the tank's water temperature to 81°F. Live brine shrimp were fed to the fish that
morning, and five of the gobies were observed eating ('gorging') for the first time, after
which they became more animated. That afternoon, live blackworms (most of which were
longer than the gobies) elicited a feeding frenzy. In contrast, three gobies remained
inactive through both feedings. I surmised that these individuals were either sick or
still stressed from the recent translocations and changes of water parameters. That
evening, two of the presumably sick gobies were alternating between whirling in the tank
and floating listlessly, their vertical bands (stripes) now a brownish color, their bodies
pinkish-purplish. The third sick goby was bloated and clearly in distress. All three died
shortly thereafter.
Water parameters and initial feeding success
I suspected ich, fungi, osmotic stress, and improper diet were jointly responsible for
a complex set of problems. Over the next seven days, the water gradually replaced until it
contained about one tablespoon of synthetic sea-salt per gallon (final specific gravity of
1.004) and was at pH 7.5, and still at temperature 81°F. Nitrobacter and Nitrosomonas
and other beneficial bacteria (Nutrafin Cycle) were added during each water change
following the manufacturer's recommendations. In response to the water parameter changes,
the glassfish started eating. Feedings were performed twice daily, once each with live
blackworms and brine shrimp (the gobies refused frozen brine shrimp and bloodworms).
Whereas the guppies and glassfish relished small fruit flies, the gobies caught but spat
them out. Soon, the results of feedings with live foods were globally apparent. First, the
guppies developed more pronounced markings and colors, especially reds and blues. Second,
the bumblebee gobies became very active, constantly darting (skipping) over and exploring
the bottom of the tank, had filled out (no longer looking 'anorexic'), and had developed
yellow-green bodies with dark black vertical bands. Lastly, the white spots were largely
gone from the glassfish, which began to develop a slight silver tinge its body.
Fortuitously, it was late April, and a discreet neighborhood pond was laden with leaves
from the previous fall and filled with water from recently melted snow. The pool was full
of planktonic life, primarily glassworms, mosquito larvae, midge larvae, copepods,
occasional daphnia, and profusions of what were likely species of bosmina and moina. These
were caught in a fine mesh net, rinsed, and added to the aquarium. In the presence of live
foods, the gobies actively swam throughout the water column in search of prey, often
sticking to the aquarium glass right under the water surface to rest as well as ambush
prey near or at the water surface. Early on, it looked like the gobies were engaging in
taste-testing sessions, probably acquainting themselves with the new food selections. The
gobies then became selective in their choice of prey, acting like gourmands. Noteworthy,
the gobies targeted mosquito larvae (not pupae), then sought large copepods. Bosmina and
moina were eaten only after all mosquito larvae were taken. In contrast, the glassfish ate
glassworms first, then midge larvae, whereas the guppies appeared to be equal opportunity
feeders. Following two weeks of feedings with a wide variety of live food, the gobies
began to increase in size. By mid-June, they had doubled in size, and had pronounced
yellow-green bodies and thick dark black bandings. Unfortunately, only Java ferns and Myriophyllum
survived in the brackish water. To compensate for the loss of cover, a barnacle-encrusted
rock was added. The barnacles formed miniature caves that were just the right sized
individual shelters for the gobies.
One day, the gobies were circling like sharks around a floating mass of Java fern.
Closer observation revealed that guppy fry (about 100) were hiding in the ferns, and that
the gobies were stalking them. A new live food source was thus identified!
Live foods were available until late July, after which a culture of Grindal worms was
obtained from LFSC. The worms were eaten by all the fish and are easy and economical to
culture. I also started growing blackworms, as the live worms purchased from a local fish
shop were of inconsistent quality, sometimes containing mostly dead worms and various
contaminants such as leeches, large white worms that looked like whipworms, and chunks of
animal bone. The presence of bone was interesting, and I began to wonder whether the
original blackworm grower had been feeding the worms slaughter-house by-products! My
blackworms are fed sinking proteinaceous fish food, such as shrimp pellets, and maintained
in unheated tubs with water changes performed every three days.
Previous experience gained during my youth fingered proper diet as a major factor
prolonging fish longevity, well-being, and breeding success. To provide a well-balanced
and varied diet on a continuous basis, attempts were made to culture Daphnia magna,
bosmina and moina species, tubificid worms, 'nutrient packed' brine shrimp, and
fresh-water copepods and amphipods. I failed at all attempts to raise daphnia (many with
attached rotifers) obtained from a nearby pond. Daphnia cysts as well as live daphnia
obtained from SSA only yielded swarms of cypris. During further exhaustive attempts to
propagate daphnia, two types of algae, Selenastrum (from SSA), and Nannochloropsis
(from FAFUSA), were grown in an attempt to provide daphnia with natural food. Both types
of algae grew luxuriously with Micro Algae Grow (FAFUSA), but failed to stimulate daphnia
cultures. Feedings with Roti-Rich Invertebrate Diet (FAFUSA) also had no effects. In
contrast, a culture of moina obtained from from FAFUSA was simple to grow on feedings of
Roti-Rich Invertebrate Diet, Selenastrum, and Nannochloropsis, as were
bosmina and moina co-cultures established from a local water hole, but these small
creatures are often ignored by adult gobies. Adult copepods cultured from a local pond are
a favorite food of the gobies. Tubificid worms (SSA) cultures were supplanted with
blackworms, which were easier to cultivate. Small, live, brackish water mysid shrimp (Mysidopsis
bahia), obtained from a colleague, were eagerly consumed by the gobies. Experiments
will be performed to determine if mysids can be cultured economically for more frequent
feedings. Brine shrimp are grown in salt water and fed a rotating diet of DT's
phytoplankton, Spirulina powder, and the following "instant algae"
products: Omega Boost and Rotifer diet (both from Reed Mariculture, Inc.) to boost
nutrition.
Freshwater amphipods (often called "freshwater shrimp") were obtained from
two sources: SSA and LFSC. From SSA, 'large' and 'small' amphipods were obtained. The
large amphipods (advertised as mostly Gammarus species) were indeed too large,
some even longer than the gobies! Hint: Raise them in containers with mesh or similar
tops. My cat is very fond of them and is now an adept "shrimper". More suitable
for the gobies are the smaller amphipods (mostly Hyallela azteca, but also
containing Gammarus species) from SSA, and in particular, unspecified rapidly
multiplying small amphipods from LFSC. The amphipods are fed live and dead water plants, Spirulina
flakes, hair algae, organic pesticide-free lettuce, and high-protein fish foods.
They are co-cultured with pond snails, which presumably digest plant material into a form
more easily assimilated by the amphipods. Noteworthy, the amphipods are remarkably
voracious. Whereas one type of pond snail proliferates to high numbers in my amphipod
growing tubs, some of the amphipods seem more interested in eating snails and snail eggs
than plants (especially if few plant leaves are present in the tub), during which time the
snails are observed to be mostly just above the water's edge as if trying to escape, and
the amphipods anxiously waiting en masse beneath. In particular, the only
remaining evidence of two large apple snails, all ramshorn snails, trumpet snails, and two
of three types of pond snails originally present and rapidly multiplying prior to the
addition of amphipods are empty shells! The amphipods provide not only nutrition, but also
sport and entertainment for the gobies, which pursue (amphipods are surprisingly fast
swimmers) and stalk small amphipods. An added benefit is that the amphipods are
detritivores and help keep the substrate clean.
To date, the sole non-motile food item consumed by the gobies has been fiddler crab
eggs. My younger son keeps four small fiddler crabs in a separate high salinity brackish
water tank (specific gravity of about 1.015). The exact crab identity/species is
uncertain, variously identified as freshwater mini crabs, Amazon crabs, or Florida fiddler
crabs by the seller. Regardless, the two females produce ample amounts of eggs, tens of
thousands of which are released at least every three months. The sooks (egg-carrying
females) are transferred to a small tank when the female's egg sponge in notably extruded
and the eggs are very dark colored, shortly before egg release. Once released, the
floating eggs are collected by pouring the tank's water through a fine-mesh plankton
collector (FAFUSA). The eggs are greedily consumed by the gobies.
Plants and hair algae
To provide a suitable habitat for the bumblebee gobies, an attempt to emulate an
estuarine environment seemed like a good idea. In the Philippines, I saw fish that were
likely bumblebee gobies in an upper estuary site, near the confluence of a large stream
("river") feeding into the sea. The estuary was subject to drastic tidal change,
the water changing from being choppy with swift currents and occasional whirlpools at high
tide to a relatively calm shallow and narrow channel at low tide. A local youth told me
that the bumblebee gobies were "batang" (juvenile) "bia" (a generic
Tagalog word for goby); a large species of saltwater "bia" was indeed part of
the local diet. At the estuary, out-flowing water stemming from the large stream was
lightly greenish and somewhat cool. Significant water flow had apparently only recently
resumed with the advent of the monsoon season. The water turned deeply green and warm
after turbulent mixing with in-flowing sea-water at high tide. Clearly, the whole area was
very productive, evidenced by a profusion of invertebrates and large schools of various
fish of different sizes, some very large and said to include sharks. Largely exposed at
low tide, the bottom was primarily deep mud, broken up by tufts of dark volcanic rock
overgrown with algae and oysters, and was littered with drift wood, sea shells, and other
debris. Mangroves lined both river banks, forming substantial groves along the stream and
becoming sparser seaward. Huge swarms of mosquitoes and other small insects hovered over
the mangroves thickets at inward locations. Mudskippers and crabs (fiddler, hermit, and
other) were abundant during low tide. The 'river mouth' widened into an area that rapidly
changed from mud bottom and dark green water to white-sand and crushed-coral beaches with
sparkling, clear water. These recollections made me wonder what might be the proper water
salinity and habitat for my bumblebee gobies?
An internet search [for example:
http://www.webcityof.com/miff1017.htm] revealed that nine species of 'bumblebee goby'
are presently recognized:
1. Brachygobius aggregatus (Philippine Bumblebee)
2. Brachygobius doriae (Doria's Bumblebee Goby)
3. Brachygobius kabiliensis
4. Brachygobius mekongensis
5. Brachygobius nunus
6. Brachygobius sabanus
7. Brachygobius sua
8. Brachygobius xanthomelas
9. Brachygobius xanthozona
Information on their maintenance was however sparse and sometimes conflicting.
According to internet information, the Philippine bumblebee goby (B. aggregatus)
requires higher salinity water than other species. Apparently, all bumblebee goby species
liked heavily vegetated habitats. I wondered which bumblebee goby species I had, and which
plants were suitable for their habitat?
The owners of the pet store from which I purchased the fish had no idea which bumblebee
goby species they sold, and neither did their supplier. According to the supplier, their
goby breeder pleaded ignorance, referring to them only as "bumblebee goby, species
unknown".
Various sources often repeated on the internet state that bumblebee gobies are best
distinguished according to anal fin spine and ray counts, together with banding patterns
[example: http://www.aquariacentral.com/faqs/brackish/FAQ6.shtml].
The most commonly encountered species distributed in the USA were reportedly B.
aggregatus (1 spine, 6 rays), B. doriae (1 spine, 7 rays), and B.
xanthozona (1 spine, 8 rays). The best guess was that the species I have are B.
xanthozona. The black bands do not go beneath the belly, the second dorsal fin is not
all black. Viewed using a dissecting microscope, however, the ray counts are not in
agreement with those reported for B. xanthozona. Two fishes that were examined
had 1 spine but seemingly 9 and possibly 10 rays. Moreover, one of the fish that died
early on looked a little different from the others, having a more elongated face, a
different looking vertical banding pattern that was interspersed with occasional spots,
and it had more pronounced eyes than the others. Perhaps the original fish breeder had a
group of mixed-species bumblebee gobies, and through sloppy breeding, had created hybrids.
Alternatively, the fish being produced by the breeder are very poor quality and contain
mutants that should have been culled! Other considerations are the effects of poor
nutrition and parasites. The exact bumblebee goby species remained unresolved, and so a
decision was made to maintain them at moderately low salinity, in water adjusted to a
specific gravity of 1.004 with synthetic sea-salt.
With regard to suitable vegetation, numerous plants said to flourish in brackish water
were tested. However, apart from Myriophyllum species and Java fern, none of the
plants obtained from area pet shops would thrive in water with a specific gravity of
1.004. These included various 'dwarf' sword plants and Vallisneria species.
Available onion plants were too big for the 10-gallon tank. It was noticed soon after
introducing new aquarium plants that hair algae was rapidly growing on many surfaces of
the tank, and that the algae was ignored by snails. Efforts to remove it were fruitless.
Microscopic examination revealed that a mixture of perhaps two types of filamentous algae
were present. The dominant species may have been spirulina. However, I soon realized that
various planktonic organisms were hiding and thriving in the algae, including motile green
algae, paramecium, copepods and rotifers. Furthermore, the gobies often rested and stalked
prey in large tufts of algae. Finally, it appeared that the gobies were occasionally
either eating the algae or something in it. Do they normally eat algae for roughage and
vitamins, and is it a normal part of their diet? Unsure of the answer, I decided to leave
the algae alone. Presently, the hair algae is kept in check by amphipods established in
the tank that graze on it primarily after the lights are turned off.
Breeding
Having by now invested so much effort with the gobies, I wondered if they could be
induced to spawn. To establish suitable breeding conditions, the original goby tank was
first turned into a species tank. Guppies and glassfish were removed, neither having
proved compatible with the gobies. In particular, the glassfish became a bully and rarely
allowed any fish into its territory, whereas the large guppies were sometimes aggressive
during feeding times, and these fish out-competed the gobies for live food.
Limited available information suggested that bumblebee gobies can be induced to spawn
by lowering the ambient salt concentration and increasing the temperature, purportedly
mimicking the effects of rain (during the rainy season). This was somewhat puzzling, as
tropical rainy seasons typically have the opposite effect on water temperature (lowering
the temperature). In fact, my past experience was that well-conditioned fish that
purportedly spawn during the rainy season (such as neon tetras, tiger barbs, blue rams,
and jewel fish) could be easily induced to spawn by partial changes with lower temperature
water.
It is common knowledge that well-conditioned fish and the proper temperature and water
conditions are essential for breeding success. My fish were clearly robust (and presumably
well conditioned) by late September. But there was a major problem. Of five surviving
gobies, only one was female, and it had a deformed tail fin. The deformed tail fin had an
abnormal lengthy extended ray or spine (reminiscent of a male swordtail), and this
hampered her swimming ability. Was this due to hybridization or genetic mutation? The
female was culled, and 12 new gobies were purchased and placed in a separate 10-gallon
quarantine and conditioning tank. Within a day, four exhibited the whirling problem
observed with the previous batch and died. The remaining eight thrived on a live food
diet, grew quickly, and all turned out to be males. Gender (sex) change has not been
reported in bumblebee gobies to my knowledge, so I asked the pet shop owner if the gobies
were pre-sexed before sale (a common practice with other fish). The pet shop owner said
with bumblebee gobies, it was all just "luck of the draw." The eight new male
gobies thrived but were especially quarrelsome, unlike the previous batch. Was this due to
having too many males in close proximity? The eight were exchanged for 12 new small ones.
Three died within two days. The new batch seemed especially malnourished, and may have
been infected with fish lice or something else, as they constantly scraped themselves
against hard surfaces. They were fed live foods and transitioned over one week to water of
specific gravity 1.008, maintained there for a week, then transitioned back to water of
specific gravity 1.004. This resolved the scratching problem, the fish grew rapidly, and
this time, out of nine fish, two were normal-appearing females. Males are distinguished by
their slimmer profile, shorter length, and a slight orange-tinge in their anterior
coloration that is visible with overhead lighting. The males of this batch were also very
quarrelsome, the four smallest males effectively collared by the others into a small
corner section of the tank much of the time.
In early December 2003, a 10-gallon breeding tank was set up with conditioned water and
substrate, and stocked with amphipods for a constant source of live food. The tank had a
crushed coral bottom, a barnacle-encrusted rock, one large strand of Myriophyllum
overgrown with hair algae, water was at 81°F, and was dimly lit with two 15 W light
bulbs. Well-conditioned gobies (two female, three male) were then placed in the tank. Over
one week, the water was changed to a final salinity of about one teaspoonful of sea salt
per gallon. To mimic the brief temperature change that occurs with rain, every daily 15 -
20% water change was performed with water at 78°F. It was hoped that the brief
temperature dip and decrease in salinity would trigger spawning. During this period, the
fish constantly swam in the upper water column, especially where the current was
strongest. Was this 'shoaling' behavior?
By week's end, the males were displaying pre-spawning behavior. They were vigorously
swaying, sashaying, and swimming above and around selected barnacles. They also had paler
black bands than usual in the posterior 2/3 of their bodies, developed a deep dark color
over the front third section of their body, and overall, their bodies exhibited an almost
iridescent orange-yellow pallor. At times, they were acting extremely erratic, darting up
and down the water column and even slamming sideways and even upside down into the
substrate, as if desperately trying to escape a predator. Their antics certainly caught
the attention of the two females, which were fortuitously seen to accompany two males into
their respective barnacle holes numerous times.
It was expected that at best, two males would be guarding eggs from two females, but
perplexingly, all three males were guarding dens. Perhaps not all were actually guarding
nests? White ovoid eggs were seen from the inside upper sides and ceiling of one barnacle
after a brief outing by the male (to shoo a large amphipod away from the vicinity). A
miscalculation, however, caused the loss of the entire first hatching(s). From internet
information, it was expected that the eggs would hatch in 5 - 10 days. Toward the end of
day four post observance of spawning, I had intended to switch off the external power
filter, and to also transfer as many adults as possible to a different tank (cognizant
that cannibalism might occur). It was expected that the males might be recalcitrant to
leave their nests and there would be the possibility that only the females might be
removed. Due to a particularly long working week, I had not removed any adults from the
breeding tank, and upon arrival late on the evening of the fourth day, found five very
rotund adults actively finishing off some slow swimming fry that were in the water column
above the barnacles! At that instance, the adult fish were reminiscent of satiated
crocodiles after feasting on wildebeest, as seen in a TV wildlife show. Eggs were no
longer visible, and water siphoned from the vicinity of the fry yielded only two small
amphipods. No evidence of surviving fry was present in the Myriophyllum and hair
algae. What happened to the limited parental attention said to be characteristic of this
fish? Had the eggs hatched earlier than expected because of good nutrition/conditions, and
had the parental guarding period also elapsed earlier? How could five fish polish off so
many fry (assuming three separate egg clusters hatched)? During a cleaning of the external
power filter, it was discovered that numerous fry (by then, dead) had been sucked into and
trapped by the filter. This demystified the seemingly improbable notion of five fish
eating all the fry from three separate hatchings in short order.
10 days later, two males were again guarding eggs in the same barnacle holes they had
previously spawned in. Knowing the eggs might hatch in four days, the females were
relocated immediately to a separate tank with similar water parameters. This time, the
eggs hatched in three days! Two rotund males were once again circling like buzzards over
the nest sites. Had the fish in fact spawned more than 10 days earlier? A chance
observation led to a new revelation: A large amphipod had clamped onto one of the fry,
presumably consuming it! Had amphipods consumed eggs also? It may not be prudent to have
amphipods in breeding tanks. Digressing here, I have noticed that counter expectations,
moina and copepods never proliferate to high numbers in my amphipod growing tubs, and have
suspected predation of the planktonic fauna by the amphipods. Indeed, when present,
fast-swimming male copepods predominate, whereas slow-moving egg-bearing females are
rarely seen, suggesting that the amphipods are capable of catching slower swimming fauna.
I have only had moderate success with cypris and amphipod co-culture; perhaps the shells
of cypris are somewhat protective.
Since I had no idea how often bumblebee gobies can be safely spawned without affecting
their health, I decided to revert the water of the breeding tank to higher salinity,
thinking this would stop spawning behavior and allow the fish time to recover. I thought
the females would need some time to develop new eggs, and the males time to replenish fat
reserves needed during nesting (when they rarely eat). For both females and males, the
water was reverted to a specific gravity of 1.004 over a week, and the breeders were then
moved back to the maintenance tank containing other gobies. The females were soon thick
again, clearly full of eggs. Instead of shoaling behavior, many of the fish were now
distinctly territorial. The two smallest males in the tank died, one with its tail fin
completely gone, one with its tail fin half gone and with severe lacerations evident in
its pelvic area. Too many adult males together in a small space? In contrast, the females
seemed to be ignored by the males outside of breeding time. So far, the only time males
have been observed aggressive towards females was when the females strayed to close to egg
clusters.
Successful isolation and rearing of fry
Internet information on bumblebee gobies (posted by various pet suppliers and
individuals) often indicates that reduced lighting is preferred for general maintenance.
To provide additional shade cover, and as a biological aid in cleaning water impurities,
duckweed was placed in a new breeding tank containing one teaspoon of sea-salt per gallon.
Prior tests showed that the duckweed thrived under those conditions, and would also
provide food for amphipods. However, an internet search yielded an interesting article by
Tom and Pat Bridges on breeding B. nunus, accessible at:
[http://www.aquarticles.com/articles/breeding/Bridges_Bumblebee_Goby.html]
In that article, they recommended not having duckweed in tanks with bumblebee goby fry,
which appear to stick irreversibly to the plant's roots. Following their advice, duckweed
was completely removed from the new breeding tank. This time (early February), conditioned
fish (two males, two females) were used, and instead of barnacles, short white PVC pipes
(capped at one end) were positioned on the bottom to provide shelter and surfaces for
egg-laying (and for positioning the opening to easily see eggs as well as for easy
extraction if desired for hatching the eggs elsewhere). Substrate consisted of dark quartz
sand. The sand had been conditioned for several weeks to 'live sand' (containing bacteria
for nitrogen cycling, and microorganisms including rotifers that would be useful as fry
food). Water conditions were as before, though the power filter was omitted and gentle
aeration instead provided by an air hose. Plentiful moina (about 1000 adults) were added
to provide constant live food, with hopes that those uneaten would multiply as well as
control excessive algal and infusorial blooms. To reduce ammonia, etc., Ultimate water
conditioner (FAFUSA) was added daily. Prior to adding fish, one ml each of concentrated
infusoria cultures (paramecium, euglena, and rotifers) and a slight amount of live algae (Selenastrum
and Nannochloropsis), just enough to give the water the slightest tinge of green,
was added. The reason for adding microorganisms at this point was not just to provide an
instant source of fry food, but also to test a hypothesis: It has been suggested that in
general, the presence of certain microorganisms acts as a secondary stimulus for the
spawning of some fish by signaling the availability of food suitable for fish fry. I also
hoped that moina would not be predators of the fry!
Though spawning was not directly observed, males were guarding eggs five days later.
The females were removed but the males left to tend the eggs. Plants (Myriophyllum
and Java ferns) likely lacking hydra and other undesirable organisms (from my other fish
tanks) were added to provide cover for the fry. The eggs hatched four days after the males
were first observed guarding them, and the males were subsequently removed. Fry from two
apparently synchronous hatchings were now swimming in their own tank and estimated to
number around 450 (more than expected).
The newly hatched presumptive B. xanthozona fry were perhaps 2 mm in length,
and they swam in the water column and below the surface (atypical demersal behavior). They
were nearly transparent except for their big dark eyes and one discernable black spot in
their body, and seemed to eat right away. They were drawn to bright light, possible
because motile phytoplankton and other infusoria often congregate in well-lit sites. With
constant gentle aeration, and without filtration, infusoria and micro-algae were added
twice daily for the first two weeks. This consisted of paramecium and rotifers (starter
cultures for both were obtained from LFSC), Selenastrum and Nanochloropus,
and euglena (cultured from a local pond). Moina remained from the primary breeding tank
set-up, and were allowed to proliferate with the assumption that young moina would act as
a primary live food source when larger foods could be taken by the growing fish. The fry
appeared to be constant feeders and losses were surprisingly negligible. Microworms (LFSC)
were used to supplement feedings beginning week two, along with moina, sifted copepods,
and brine shrimp nauplii. The juveniles developed stripes like their parents by the end of
week three, and started exhibiting demersal activity. To keep them away from the water
heater, additional plants and conditioned rocks were provided. Throughout this period,
daily 10% water changes were made with pre-aerated water that had been pretreated with
water conditioner and warmed to 81°F. Commencing week four, the water salinity was
gradually transitioned to a specific gravity of 1.004 over a two week period, and a sponge
filter was utilized. Growth seemed especially pronounced after the water salinity
was increased, but this is a topic for further research. Finally, it was noted that the
fry appeared to be eating something on the surface of the quartz sand substrate.
Microscopic examination revealed that in addition to rotifers and other microfauna, the
quartz substrate contained small, active, water worms. Whereas the identity of the worms
is presently unknown, it is surmised the gobies were eating them in addition to rotifers
and other microfauna, and may be an important part of their diet.
Summary of lessons learned
1. Sellers may not know which species of bumblebee goby they sell.
2. Common sense dictates that to reduce the hazards associated with wild-caught live foods
(such as parasites), home-cultured foods are preferred. Amphipods are seeded into the tank
and allowed to proliferate (and the stock replenished as necessary), and together with
Grindal worms, phytoplankton-fed brine shrimp, and blackworms, serve as the basal diet.
For variety and possibly added nutrition, the gobies are also fed baby guppies, planktonic
foods (especially copepods), and perhaps, small mysid shrimp.
3. Based on variables such as increased growth rate and activity, it is likely that these
fish prefer to live in higher salinity water than the lower-salinity water they spawn in.
4. Well-conditioned fish maintained in water at specific gravity 1.004 will spawn readily
when the water salinity is reduced. Serial spawnings can occur at 7 - 10 day intervals.
5. Under conditions of reduced salinity, 81°F, and with well-conditioned fish, eggs may
hatch in four days. Note: The thermometers used in my tanks may not be very accurate; in
one test, the temperature reading was around 79.8°F (instead of 81°F) when measured with
a high-quality laboratory thermometer.
6. It appears that males should not be crowded together!
Recent observations
In comparative tests using some of the fry above, increased calcium concentrations in
tap water (obtained by adding kalkwasser) did not act as an adequate substitute for
sea-salts. Under these conditions, the fry grew at a slower rate than those in water with
sea-salt. It is not sure if slower growth occurred because they required trace elements
found in sea-salts, or perhaps, magnesium concentrations needed to be raised or maintained
in some optimal ratio with calcium, considering that magnesium is an important component
of sea-water.
The addition of Tetra Blackwater Extract to the breeding tank produced the largest
number of fry to-date (Feb. 24, 2004) from a single spawning (about 320). To
reduce carbonate concentrations, quartz (instead of coral) substrate was utilized. It is
not yet clear if more fry resulted because of the added extract, or because two
well-conditioned mature and experienced breeders were used. Note: In my
tanks, hair algae seems to start growing immediately after the addition of Tetra Backwater
Extract!
Not mentioned above, some of the last batch of fish that were purchased may be
permanently stunted. Even when separated from perhaps dominant fish and placed in a
separate tank, they have not grown to the same size as their cohorts. Poor early nutrition
is suspected.
One last item deserving further observation: It is possible that occasional doses of
supplementary iodine are beneficial. Tests with some of the fry above indicate that growth
is faster when iodine is added to the water. It is not clear if the effects are direct
(iodine might be essential for normal development) or indirect (such as if iodine is
reducing the growth of harmful microorganisms).
Closing remarks
It is always heart-breaking to purchase malnourished, sick, and genetically impaired
fish. Fish shop owners should voluntarily refuse to sell poor stock and be more sensitive
and attentive to this issue. Unfortunately, at least locally, the low prices charged for
many fish creates an economic disincentive for the sellers to be overly caring; it is too
costly for the sellers to maintain quality fish, and customers are willing to endure fish
losses due to low costs. It is a pity that many consider these living creatures merely as
living decorative but disposable commodities.
Going full circle, tribute goes to the "low tech" Filipino shop owner of so
long ago who was in reality more knowledgeable about the fish he was selling than the
present-day experienced American shop salesman in the high-tech shop filled with
every modern aquarium contrivance imaginable. Buyer beware, or should salespeople be
truthful and only state facts based on reasonable levels of knowledge?
Lastly, much still needs to be learned about the basic biology of these fish. For
example, is there an optimal temperature for egg development and hatching? Does water
hardness affect egg hatching? It seems timely to initiate a breeder's association and
genetic database to properly establish bumblebee goby species identity and to maintain the
long-term purity and vigor of these fascinating and pretty fish. A handy reference book is
also long over-due…attention booksellers?
Sources and miscellaneous tidbits
Aquarium salt: Doc Wellfish's Aquarium Salt, Aquarium Pharmaceuticals, Inc., PA. DT's
phytoplankton (Sycamore, Illinois).
FAFUSA; Florida Aqua Farms, Inc., USA, Dade City, Florida,
LFSC; L.F.S. Cultures, University, Mississippi Nutrafin Cycle, R. C. Hagen (USA) Corp.,
Mansfield, Ohio
Reed Mariculture, Inc., Campbell, California
Sea-salt: Reef crystals, Aquarium Systems, Ohio.
SSA; Sachs Systems Aquaculture, St. Petersburg, Florida
Ultimate water conditioner; FAFUSA
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