By Don Kinyon
One of my favorite pet shops is a very small independent store that stocks mostly the bread-and-butter varieties of aquarium fish, but every once-in-a-while will have some more unusual stock for sale. As I was wandering through the place one weekend I found some fish that I'd never seen before. There was a tank full of tetras, similar in body shape to a bleeding heart or a rosy tetra, but more colorful and very eye-catching. Most of the bodies of the fish were a pinkish-white, while their bellies and heads were more gold. Their pectoral fins were almost clear, the tails were clear with bright red ovals on the upper and lower lobes. The anal, pelvic and dorsal fins were bright red near the body, turning white towards the tips. There was a splash of black on the dorsal fin as well. These were really good-looking fish!
The fish were relatively cheap, so I took ten of them home and put them into a 40 gallon tank that had recently held some Apistogramma species. The water was set-up for Amazon region fish, so it was soft, acidic, and brown: around 100 PPM TDS, 6.0 pH, and 76° F. Filtration for the tank was an outside HOT filter with a foam block on the intake to keep small fish from entering. Most of the tank bottom was covered with java moss with some java fern mixed in.
These fish would eat anything offered and it seems that they are always hungry. Most mornings they would get flake food and some newly hatched brine shrimp, and in the evening they'd have either live or frozen food: black worms, white worms, daphnia, mosquito larva, blood worms, or glass worms. The type of food didn't seem to matter; as once it hit the water it was history!
My HY511 tetras were fairly young when I first got them and the sexes were hard to tell apart, so there was not much to do but feed them and watch. Once the newness wore off they were pretty much forgotten for a while. What got them back into the forefront of my attention was quite accidental. I often "spotlight" the fish after the lights go out for the evening to see what's going on with them. It's especially useful with Corydoras or other semi-nocturnal fish and shows behavior that the fishkeeper may not see during the daylight. When I was using this technique one evening I happened to look into the HY511 tank and saw what looked like some tiny shards of glass in the java moss near the bottom of the tank. Once I put my reading glasses on, I could tell they were young fish: probably half a dozen or so, and very small.
The next day I prepared another tank for the adult fish and moved them, trying to disturb the rest of the tank and the fry as little as possible. Of course, that never works and I made a complete mess of the aquarium. That night I spotlighted the tank once again and found that about a dozen youngsters could be seen darting around in the moss.
The young fish grew fairly quickly and soon would take the same foods as the adults, though in smaller sized pieces. There turned out to be about twenty; not really as many as one would expect from a group of tetras, so when they were mature enough I removed them to another tank and picked out two males and one female from the original adult fish to go back into the breeding tank. By now the adults are very easy to tell male from female: the males have an extended dorsal and get larger than the females. They also tend to be more brightly colored. The females keep an oval-shaped dorsal fin, same as the young fish and the dorsal tends to have more white on it. They don't grow as large as the males, but are thicker-bodied.
The breeders were fed at least twice a day with live foods and soon the females were robust and all the fish were very active. One day during the evening feeding I noticed the female was no longer as stout as she was that morning; she'd lost a lot of weight! Immediately the breeders were removed and joined the rest of their group in another tank. Then the waiting started. It was five days before any trace of young could be found, and there were only a few... at first.
By the next day there were more fry, and the following day; many more. Soon there were far too many to count. When I felt the young fish were mature enough to stand the stress I started daily water changes in their tank; first with rain water, then a mixture, then with well water. It did not seem to harm the fish at all; they grew faster with the constant fresh water. Soon fish from two other tanks were evicted from there homes in order to find more space for the young tetras and before it was over, the original 40 gallon, a second 40, a 55 and a 125 all had HY511 fry growing out in them. Even at that, there was some crowding. The fish room was being overrun! It's only a guess, but I'd estimate there were easily over 400 of them.
When no more than a few days old, the young HY511 would eat newly hatched brine shrimp until their bellies bulged a bright orange. They are ravenous even at this age. Growth was fairly rapid and at 10 days the fry had grown into the same ovate body shape of the adults. Finely crushed flake food was added to their diet about this time and they ate it with almost as much vigor.
When the tetras were around four weeks old and one half inch in length, I started selling them at aquarium society auctions, labeling them as "10 juveniles," but putting 15 or 16 in the bags. This made a lot of bidders happy and gave me some breathing room in my tanks. Once they were down to occupying only two tanks (one of them a 125 gallon), I slowed the sales to a more moderate pace. Pet shops won't give too much for most tetras, but I found that most local shops were happy to trade HY511 for at least some store credit. Finally, months and months later, things have calmed to normal and only one tank holds the now-adult remnant of the HY511 brood.
This morning I set up two pairs in a 40 gallon tank with some java moss.