FOOD
37
pelleted foods that sink are available or one may make
a paste of finely ground food and drop small balls of
this into the tanks. Another method of feeding food
in paste form is to force it through a potato ricer. This
procedure greatly reduces the tendency of these
foods to become dispersed in the water and cause a
polluted condition.
The amount of food to be fed is of special concern
in the use of compounded rations. Overfeeding results
in polluted conditions that can cause the loss of fishes
by oxygen depletion. Most fishes will utihze daily a
quantity of food amounting to approximately three
percent of their body weight. One can start feeding
at this level and adjust the amount on the basis of the
amount that appears to be successfully utilized. In
actual practice one may measiu'e the volume corresponding to the weight to be fed daily and then feed
by volume.
DRIED FOODS : The wide availability of commercial fish feeds has ehminated the necessity of compounding one's own ration. The pelleted, commercial
rations have the added advantage of the components
being bound together during the pelleting process.
This avoids the problem of selective loss of components by variation in solubiHty. The author prefers a
commercial trout pellet ground to a size appropriate
for the fish being fed.
Gordon's liver-cereal ration: Gordon
(1950) suggests a mixture of a pound of beef Hver,
20 tablespoonfuls of Pablum, and 2 teaspoonfuls of
table salt mixed to a paste consistency. The liver is