Many fish—for example large marine angelfish, which feed primarily on sponges—have a diet that can be difficult to replicate in captivity.
groupers, eels, and pufferfishes. They
naturally prey upon a variety of animals such
as worms, mollusks, crustaceans, and fish.
The diet of predacious fish should be
composed of at least 75 percent whole food
items. Whole food items are animals that have
not been prepared, processed, cleaned, or
gutted, but rather offered to fish as they were
in life. Readily available whole food items may
include fish, crustaceans, squid, octopus, and
mussels. The remaining 25 percent or less can
be fish fillets or other meat-only items.
Frozen and thawed shrimp, krill, prawn,
plankton, silversides, sand eels, squid, and
octopus can all be offered to predacious
fish. Many of these foods are readily
available and can be found in their natural
form, but frozen. If possible, frozen foods
and frozen formulas should be fed before
live food items. Any food offered should be
cut up into bite-size portions.
If they are absolutely necessary to entice
picky eaters, live foods should be chosen
with care so parasites and diseases are not
introduced. Ideally, live food should be
quarantined and treated before it is added
to an aquarium.
Groupers that do not receive a varied diet
or that are given one that is heavy in feeder
goldfish are prone to head-and-lateral-line
disease. Lionfish and frogfish are prone to
lockjaw when they are fed a lot of goldfish.
Predators also often die from an impacted
gut when their diet is heavy in feeder
goldfish. The gut blockage is caused by the
large skull of a feeder goldfish that becomes
stuck inside the predatory fish and blocks
the passage between the stomach and the
intestine. Lionfish and frogfish frequently
succumb to death by a goldfish diet.
Herbivorous fish are those whose main
food source is plant matter, or in the case
of marine herbivores, algae. Lawnmower
blennies, tangs of the genus Zebrasoma,
some dwarf angelfish, and rabbitfish are
generally considered herbivores. These fish
spend their days grazing on various macro-and microalgae.
Tropical Fish Hobbyist www.tfhmagazine.com