SELECTION OF FISHES
33
is small enough, about 1.5 inches, that only the most
limited facihties are required. Its shortcomings include being too small to be injected or to be weighed
conveniently. Like most "tropicals" the zebra should
be maintained at a temperature of 75° to 80° F.
To spawn this species, one should place several
males and females in a cage of nylon marquisette
suspended in an aquarium. Water depth in the tank
should be only three or four inches. The cage should
be suspended approximately one inch above the bottom of the tank. When the fish spavvoi, the eggs fall
through the netting and escape being eaten. Zebras
may also be spawned over gravel, but a large tank is
required.
Bullheads (Ictalurus spp.) are available in most
areas of the United States. They can be held in
aquaria but are especially recommended for short
term studies involving bringing experimental fishes in
from the field. Bullheads will feed on meats or meals.
They respond negatively to hght and are probably
more suitable as experimental fish when kept in subdued fight. In smaU ponds bullheads tend to become
very numerous, and by seining one may frequently
obtain large numbers of uniform size.
There exists considerable interest in the culture of
channel catfish (Ictalurtts punctatus). This has resulted in the accumulation of knowledge concerning
this species and has made channel catfish of all sizes
available commercially. Notable among the areas
where this culture is being practiced are Arkansas and
Mississippi. Eggs of the channel catfish can be obtained by use of fish pituitary extract or even chorionic
gonadotrophin. Catfish can be crowded and fed
33
is small enough, about 1.5 inches, that only the most
limited facihties are required. Its shortcomings include being too small to be injected or to be weighed
conveniently. Like most "tropicals" the zebra should
be maintained at a temperature of 75° to 80° F.
To spawn this species, one should place several
males and females in a cage of nylon marquisette
suspended in an aquarium. Water depth in the tank
should be only three or four inches. The cage should
be suspended approximately one inch above the bottom of the tank. When the fish spavvoi, the eggs fall
through the netting and escape being eaten. Zebras
may also be spawned over gravel, but a large tank is
required.
Bullheads (Ictalurus spp.) are available in most
areas of the United States. They can be held in
aquaria but are especially recommended for short
term studies involving bringing experimental fishes in
from the field. Bullheads will feed on meats or meals.
They respond negatively to hght and are probably
more suitable as experimental fish when kept in subdued fight. In smaU ponds bullheads tend to become
very numerous, and by seining one may frequently
obtain large numbers of uniform size.
There exists considerable interest in the culture of
channel catfish (Ictalurtts punctatus). This has resulted in the accumulation of knowledge concerning
this species and has made channel catfish of all sizes
available commercially. Notable among the areas
where this culture is being practiced are Arkansas and
Mississippi. Eggs of the channel catfish can be obtained by use of fish pituitary extract or even chorionic
gonadotrophin. Catfish can be crowded and fed