Comments. RES and about all fish by themselves will tend to stunt due to "too many hogs feeding at the table - quote Lusk") - limiting food reserves. Res in a mixed fish population where food is limited I assume there is competition among the species. Each species often feeds on different types of foods or is able to multi-task foods. RES will feed on snails - mollusks usually not utilized by other fish. Then with predators present they will usually "thin the herd". Plus in a mixed fish population RES are at a disadvantage by having low reproductive potential compared to other species present. Few RES are produced thus the low numbers of fry get consumed quicker compared to species with abundant fry. It is primarily a complex competition thing. I consider RES to have a low competitive advantage. Slow growing fish stay small longer and likely are weaker or have health issues (lack of food) thus are more likely to get eaten in presence of predators. In nature generally the fittest survive.
In RES only situations (some fish farms), crowding leads to forcing RES to feed on non-preferred items, resulting in inefficient non optimal feeding, resulting in poor growth. Fish can often survive for months without measurable food. Fish can be kept in a bucket or pond of good quality water for a long time before they starve to death. Without predation too many fry survive and those fry will have poor or very little or no growth but may not completely starve to the point of death. Put in a good food habitat the growth will resume but these fish will not regain those days of growth that were lost.
For a very good discussion of fish growth and indeterminate growth see the current issue of Pond Boss Jul-Aug 2014 pg 22, "Fish Biology 102: Growth" by Bob Lusk and Dave Willis. Some quotes: "If there are insufficient resources for growth, fish stop growing, but not necessarily die. If resources become sufficient .... fish can resume growing. Fish growth is very much dependent on population density (abundance)."
Last edited by Bill Cody; 07/28/14 09:00 AM.
