30
MAINTAINING FISHES
there are significant phylogenetic diflFerences. It is
well to break the group into a number of subdivisions, namely: clupeids, cyprinids, cyprinodontids, and
percoids. Selection of representatives from this large
group constitutes a rather complex problem.
Clupeids
We know more, perhaps, about maintaining
trout {Salmo gairdner, S. trutta, Salvelinus fontinalis)
in captivity than about any other group of fishes.
Various pubhc agencies have done a great deal of research on their care and culture. Their environmental
and nutritional requirements are known and rates of
growth and other standards of comparison are available. Trout have some attributes which make them
especially suited to experimental use. They are easily
obtained from private, state, and federal hatcheries,
and with plenty of fresh, cold water may be maintained in very dense populations. They feed readily
upon nonHving foods including liver and heart as well
as recently available pelleted food. On the negative
side, trout require temperatures of about 60° F. and
are best maintained in running water. To work with
trout, one should have an abundance of spring or well
water. Further, large trout require rather elaborate
facihties.
Mud minnows (Umbra limi and U. pygmaea) inhabit small ponds and back waters, and are especially
abundant in permanent swamps. They occur in the
wild in the Mississippi drainage, Great Lakes drainage and Atlantic coastal areas. In nature they feed
upon aquatic invertebrates. They would very likely
utilize earthworms or tenebrionid larvae. As experi-
MAINTAINING FISHES
there are significant phylogenetic diflFerences. It is
well to break the group into a number of subdivisions, namely: clupeids, cyprinids, cyprinodontids, and
percoids. Selection of representatives from this large
group constitutes a rather complex problem.
Clupeids
We know more, perhaps, about maintaining
trout {Salmo gairdner, S. trutta, Salvelinus fontinalis)
in captivity than about any other group of fishes.
Various pubhc agencies have done a great deal of research on their care and culture. Their environmental
and nutritional requirements are known and rates of
growth and other standards of comparison are available. Trout have some attributes which make them
especially suited to experimental use. They are easily
obtained from private, state, and federal hatcheries,
and with plenty of fresh, cold water may be maintained in very dense populations. They feed readily
upon nonHving foods including liver and heart as well
as recently available pelleted food. On the negative
side, trout require temperatures of about 60° F. and
are best maintained in running water. To work with
trout, one should have an abundance of spring or well
water. Further, large trout require rather elaborate
facihties.
Mud minnows (Umbra limi and U. pygmaea) inhabit small ponds and back waters, and are especially
abundant in permanent swamps. They occur in the
wild in the Mississippi drainage, Great Lakes drainage and Atlantic coastal areas. In nature they feed
upon aquatic invertebrates. They would very likely
utilize earthworms or tenebrionid larvae. As experi-