By Donna M. Recktenwalt
As amateur aquarists, we keep our tanks clean, our fish healthy, and often breed and raise them. But the route from egg to adult fish is a perilous one, filled with potential problems. Many of us find that raising fry is a skill we need to work on.
“The size of the adult fish is determined in the first few days of a fish’s life,” says Ralph Taylor. “We as hobbyists need to do a much better job at getting very small fish off to a good start.” Many fry require infusoria or plankton as a first food; microworms and brine shrimp nauplii are often too large. “If I can get [fry] through the first few days until they are large enough to take brine,” Ralph says, “I can usually keep the survivors through to adulthood.”
“I routinely feed paramecium to my fry (essentially all Nothos),” says Barry Cooper, “but I find it hard to tell whether they eat them.” Vinegar eels, he says, “are a fantastic early food.” Barry drains measures of vinegar eel culture through 10 micron nylon mesh, which results in “swarms of eels forming little aggregates.” These are rinsed with water, placed in a glass, and “squirts” fed to the fry. The eels remain suspended in the water, and can live at least 24 hours; “continuous food, less pollution risk,” says Barry.
“Do frequent water changes,” recommends Eric Lund, who has raised numerous species, but now specializes in annuals. “The more frequent the better. At high fry densities twice weekly changes of 25-30% of the water work for me.” He adds that he finds fry at the 1/2″ size to be problematic, since they are too small to eat many foods, yet require a LOT of food to fill up. He recommends varying the diet; “there’s little doubt that a varied diet will increase growth rates.”
Eric also finds that ramshorn snails are very good at cleaning up any uneaten dead shrimp, and that fry tanks with snails and java moss have fewer problems than those containing only water and fry.
— G.C.K.A. Newsletter, July 1998