Instant Corydoras paleatus (just add water)
by DeWayne L. Duff (D²)
of San Antonio
Original to Aquarticles.com
In early 1999, I bought a pair of Corydoras paleatus (peppered corys), which I
placed in a 42 gallon hex along with five rosy barbs and a Hypostomus plecostomus
(sucker fish or algae eater). After three weeks I made a partial water change. Several
days later, I walked through the room and noticed over 100 eggs spread throughout the
walls of the aquarium, in clusters of three to six or seven. What a surprise! I had owned
a pair of albino corys some years back, but never had any success in breeding them. So
this event was both satisfying, and elusive to me.
We weren't trying to breed the fish at all, and I actually found it surprising that
they would mate with the other species present. I had just assumed the corys would
perceive the others as a threat to their eggs. Because we weren't planning on this, I had
taken no steps to make the environment more suitable for breeding. The water, which I had
no way of testing at the time, was about 75% filtered (reverse osmosis) bottled drinking
water, and about 25% tap water, with the aquarium at a fairly stable 78 degrees F. Because
we live in San Antonio (tap water supplied by the Edwards Aquifer), our tap water is
especially hard, but given the mix with filtered water I thought the hardness of the water
would be suitable for the fish, but not really suitable for mating. Clearly, I was wrong.
Since that time we've had great success, with frequent breeding at least four to six
times a year, but we didn't at first, until I found out a little secret. Most corys in
their native habitat (South America, mostly Brazil and Argentina) find breeding more
appealing when they are exposed to new mates. When and how does this happen? Seasonal
rain, at least on a small scale, results in rising water levels in adjoining small rivers.
When this happens, generally it is accompanied by a drop in temperature as water flows
from one branch of a river into another, carrying along with it a flurry of prospective
new breeding partners.
Unlike our more human practice of finding romance in the warm spring, corys are
actually warmed up, so to speak, by slightly cooler water. So when I made the water
change, I inadvertently dropped the aquarium temperature by about five degrees.
Fortunately, I added the water gradually, so as not to put any of our fish into shock. But
the result was that a slight drop in temperature, in conjunction with a small change in pH
balance, re-enacted seasonal events associated with finding new mates. We've recreated
this process frequently, and find that it is the perfect formula for "instant Corydoras
paleatus (just add water)"!
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