COMPATIBILITY BETWEEN INVERTEBRATES AND MARINE FISH
Invertebrates cannot cohabit with just any fish, for a number of reasons. The
first is that they are liable to become prey for carnivorous fish. Coelenterates
are completely incompatible with angelfish (Pomacanthids), for example. Secondly,
some lively and active fish, of over 10-15 cm in length, can jostle and disturb
invertebrates in the aquarium.
Furthermore, the bigger and more active a fish, the more it excretes nitrogenous
substances, leading to the accumulation of nitrates (NO3-), which are harmful to
invertebrates. It is therefore best to avoid the presence of this type of fish.
Too many fish produce the same result and the same degree of harm for invertebrates.
Finally, there is another problem when a sick fish has to be treated, particularly
with substances containing metals, which are toxic for most invertebrates. Remember
that it is always preferable to nurse a fish in a hospital aquarium.