Planktonic Substitutes in the Aquarium
By Jason Kim
Jason is the founder of AquaC. Inc.
From his web site www.proteinskimmer.com
Aquarticles
I would like to discuss the vital role that planktonic food plays in coral reef
ecology. It might be interesting to note that before the popularity of wet/dry trickle
filtration, high intensity fluorescent lighting, and protein skimming (among other
developments in the reef hobby), aquarists placed more importance on their corals' need
for live food. Unfortunately, many of these advanced hobbyists were ignorant to the fact
that sunlight, the source of energy for photosynthesis, was just as vital a component in
healthy reef ecosystems.
A few weeks ago I was doing some research at the Scripps Institute of Oceanography and
happened to come across an aquarium "how to" book written during the late 1960s.
In the short section dedicated to coral care the author did hint at the importance of
light.
He wrote, "your corals should be placed in a shallow dish once or twice a week and
placed outside to be sunned."
I found this advice hilarious, given the fact that tanks illuminated by 400-watt metal
halide lamps are hardly a rarity these days. But it really was an insightful bit of
thinking back then. The author also stressed the need for live food, and recommended that
corals be hand-fed, by pipette or turkey baster, live baby brine shrimp or mosquito
larvae. I think that he hit the nail on the head. Even though plenty of aquarists might
scoff at this outdated book today, the author probably possessed more wisdom and insight
than some of the most sophisticated "techies" today.
As I mentioned before, the importance of live food has always nagged at the back of my
mind… but never really struck me until I watched, while diving, a wild pocillopora
colony enthusiastically pull hundreds of organisms from the water like a vacuum cleaner.
Now we are posed with two questions:
1. If we decide to feed our corals planktonic food on a regular basis, in order to
replicate the nutrient uptake levels they experience in the wild, won't we be adding
excessive organics to the system and prompt an algae outbreak?
2. What in the world can we feed the corals anyway?
I certainly don't have access to live plankton! The answers to the two questions are
remarkably simple. I stressed the need for a large, efficient protein skimmer in one of my
past articles. As long as you have a skimmer that can pull waste and excess organics out
of the water, you should be fine. Out-of-control algae growth, often of the
"hairy" or "bubble" varieties, is truly the nemesis of the reef
aquarist. Large protein skimmers can pull so much waste out of the water that the addition
of food to the tank should have a negligible effect on water quality. In fact, adding this
extra food to the tank might even benefit the overall health of the tank, especially the
vitality of your soft corals. If you are running your tank skimmerless, or with one of the
less efficient models available, I would recommend upgrading to a higher quality skimmer
and bump up the feeding regime. If this is not an option, add food slowly and monitor your
water quality carefully (you should be doing this, regardless) to see how far you can
"push" your limits without getting extra algae growth. All tanks are different,
regardless of their skimmer or filtration, and you should always be careful when changing
your husbandry techniques.
The answer to the second question is simple, but might leave some of you unsatisfied.
Since live food is so hard to come by, we must settle for whatever substitutes we can
find.
Live baby brine shrimp (some people, usually those who just shelled out $29.95 at Toy's
'R Us, call them "Sea Monkeys") can be purchased at your local tropical fish
store and raised in a small bucket in the garage.
Some reef-oriented stores sell packages of live, frozen, or vacuum packed foods like
lobster eggs, mysid shrimp, insect larvae, etc. These are all viable alternatives. I've
fed my small polyped stony corals a special mash I make from store-bought seafood. Large
polyped stony corals like Catalaphyllia (Elegance coral) and sea anemones can be
fed small pieces of chopped raw squid, shrimp, clam, or fish. I feed mine once or twice a
week. I don't feed them huge amounts of food since they are accustomed to catching small
organisms in the wild on a constant basis. Remember, you should not stuff your corals as
if they were at an all-you-can-eat buffet.
Jason's Special Reef Mash (a name I just though of 10 seconds ago)
1/2 CUP RAW TIGER SHRIMP (SHELLS, GUTS, YOU NAME IT)
1/2 CUP RAW SQUID
1/2 CUP KRILL
1/2 CUP UNCOOKED SPINACH
and here is the interesting part...
1 TBS. KALKWASSER
1 TBS. MARINE DELUXE*
Chop up all the ingredients in a blender until you have a uniform slurry (not quite
watery - you want little pieces the size of brine shrimp or larvae). I then strain out the
watery leftovers and spread the mixture onto a flat sheet, which I then freeze. Every
other night or so I break off a marble-size chunk of the special mash and place it in a
cup of warm water to thaw. I then use a medical syringe to feed my small polyped stony
corals individually, with the powerhead and return pumps off. After about ten minutes I
turn the powerheads back on, but leave the main circulation pump off for another hour or
so. This allows whatever is left of the mash to circulate through the tank completely,
without being skimmed away. My hermits, echinoderms (brittle stars), and other detrivores
(creatures that eat detritus, or organic waste) consume whatever remains in the tank.
*The Marine Deluxe is a product you may or may not be familiar with, but it is
essentially a mix of vitamins, essential elements, and some other stuff which the company
refuses to divulge to the public. If you can't get your hands on this product, don't
worry. I doubt it is anything special, regardless of what they would have you believe. I
bet Combisan would work well, or any of those other full spectrum "trace
element" solutions you can find. For those daring aquarists, it might be a worthy
experiment to try dosing Iodine, Strontium, etc. via food. I have never personally tried
this and cannot guarantee that there will be no harmful side effects. I do add the
kalkwasser to try and simulate the calcareous nature of some plankton exoskeletons. Give
it a try!
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