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
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.