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Excerpted From: So
you think livebearers are boring? There’s
more to livebearers than guppies. Neale Monks looks at some of the
interesting and unusual livebearers available to aquarists
by Neale Monks
The Goodeidae
Although the splitfins have been overshadowed by the poeciliids, they
remain good aquarium fish and in recent years a fair number have become
quite commonly traded. For the aquarist wanting to try their hand at one
of “rare livebearers”, Goodeids are an excellent choice. Most are hardy,
easy to keep, and do very well in the hard, alkaline water typical of
much of England. If they have one failing it is that many are a pushy,
even nippy, fish that don’t always play nicely with their tankmates. But
kept with their own kind, or robust species such as catfish, and these
are colourful and fascinating animals.
What sets the Goodeids apart from the poeciliids is that they are
viviparous fish rather than ovoviviparous ones. In other words, they
become pregnant in the same way mammals do, with the embryo being
connected to the mother via a placenta-like structure called the
trophotaenia. This allows these fish to produce larger, more fully
developed offspring than the poeciliids. Indeed, immediately after
birth, the sharp-eyed aquarist will spot the remains of an umbilical
cord trailing off the belly of the newborn fish. On the other hand,
since the individual fry are quite big, typically around 2 cm long at
birth, the broods are rather small, often in the high teens or low
twenties.
Two
species of Goodeid are widely sold, Ameca splendens and
Xenotoca eiseni. Both are hardy, reliable fish for anyone wanting to
keep oddball livebearers. They aren’t perfect community fish though, and
this is perhaps the only thing that limits their popularity, as both are
very pretty and lively little fish. Compared with the common poeciliids
like guppies, both these species can be aggressive towards one another
and any tankmates kept with them. Of the two, Ameca splendens is
perhaps the most easily kept with tankmates. While it is aggressive and
will bully things like tetras, rainbowfish, and Corydoras
catfish, more robust tankmates, such as armoured catfish, sturdy barbs,
and semi-aggressive (but non-predatory) cichlids generally work well.
Xenotoca eiseni is similar in temperament but is also a fin-nipper,
so tankmates that move slowly or have long fins should be avoided.
All
Goodeids need a lot of algae in their diet, and unless fed copious
quantities of greenstuffs, they tend to lose their bright colours. This
is one reason they tend not to look especially exciting when held in
retailers’ tanks, where they receive only standard-issue flake food. On
the upside, being largely vegetarian, most Goodeids show little tendency
towards eating their offspring, and in a well-planted aquarium, the fry
can be raised with their parents. |
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