Some fry, such as channel catfish, can be grown on artificial feeds alone, but even these fry will grow better and be healthier when zooplankton are present.
However, an objective in all fry culture is to train the fry to eat artificial feeds, because fry ponds are stocked at densities so high that natural foods alone cannot sustain good growth of fingerlings.
Unless fish are adapted to filter feeding (such as paddlefish) they expend more energy catching zooplankton than they derive from eating them. At some point, fingerlings will be consuming zooplankton faster than it can be produced in the pond. By that time they should be well on their way to learning how to consume artificial feeds.
This learning process should be completed before zooplankton stocks are exhausted. Sometimes, however, small fingerlings are brought into tanks and trained to eat manufactured feed.
This abrupt change from natural feeds can cause high mortality. It is better to wean fish to manufactured feeds by a process called “feeding the pond.” Feeding the pond means spreading finely ground feed across the pond at a rate of about 10 to 50 percent of the weight of fry in the pond.
It is hard to determine the weight of the fry, so the typical amount used is 1 to 2 pounds of feed per acre for small fry and 4 to 8 pounds of feed per acre for catfish and other large species. The fish should be fed twice a day for 3 weeks. For small fry, use the finest size feed available.
For larger fry, a fine crumble may be used. After the initial 3-week period, increase the amount of feed to 3 to 7 pounds per acre (12 to 24 pounds for large fry) applied twice a day for another 3 weeks.
At the same time, increase the size of the feed. After the second 3- week period, check to see if the fry are large enough to eat a crumbled feed. When the fish begin to take feed at the surface, the amount of feed offered can be adjusted to meet their needs by watching the fishes’ behavior.
Feed just a small amount more than they immediately consume and later check to see if the additional feed is eaten. Adjust the amount of feed offered accordingly. Fry feeds have a higher protein content than feeds for larger fish, because fry are growing at a faster rate and must consume large amounts of protein and other nutrients.
Fry of fish that are piscivorous (fish eaters), such as striped bass and their hybrids, require a protein content of about 55 percent. Minnows and catfish require feeds with 40 to 50 percent protein. The general rule is that the higher the adult fish are on the food chain, the more protein the fry require.
Most fingerling producers remove their fish from the ponds and sell them, or restock them at lower densities, at the time when natural food in the pond can no longer support the standing crop of fingerlings.
A fingerling operation that is carefully planned and based on what is happening in the pond has the best chance of being profitable.
Author:
Gerald M. Ludwig
