Research Items

Abstract

Causes of Death in Fishes in Captivity A REPORT on the causes of mortality of fishes exhibited in the New York Aquarium at Battery Park, New York City (now closed), is given by Ross F. Nigrelli (Zoologica. Scientific Contributions of the New York Zoological Society, 28, Part 4, No. 22; 1943). Careful attention and research have reduced the mortality very considerably in the last few years and all diseases and epidemics are well under control. There are many factors, however, which may cause death besides parasites and disease. Overcrowding is important, sudden change in temperature, the wrong adjustment of light, range and degree of pH, density, amount of oxygen, chlorine and nitrogen in the water, metabolic waste products and diet—all cause mortality; also too much handling and too frequent removal from one tank to another. It is established that the fishes themselves contribute largely to their own well-being in fitting themselves to their environment. There is a definite population density of fishes for a given volume of water and the fishes will kill one another off to maintain equilibrium when all other ecological factors are equal. They can, and do, control to a certain degree the chemical contents of their environment. This paper is full of valuable information and should be studied by all who are interested in aquaria.