BACK TO BASICS: oxygen and Carbon dioxide management in hatcheries

摘要

The most important factors in keeping fish alive in a hatchery or fish farm are water and oxygen. In terms of space, the fish does not actually require much water. The problem in aquaculture is to replace the O_2 and remove the metabolic wastes. The gills take up O_2 from the water and excrete the CO_2 at a ratio of approximately 1:1.4, or in other words, for every IKg of O_2 consumed 1.4Kg of CO_2 is produced. Oxygen consumption by the fish is commonly measured in mg O_2/Kg fish//hr. The main factors affecting O_2 consumption in fish are temperature, feeding rate, size of fish and levels of activity. Small fish actively feeding at high temperatures with high water flows have the highest consumption where the lowest consumptions are seen in large fish at low temperatures and correspondingly low feed rates. There are various tables and graphs from historical studies of O_2 consumption in fish, especially salmonids. One for Atlantic salmon can be seen in Table 1 below.