We are getting a bit spoiled here at DLS having a guest blogger with such prolific knowledge of fishkeeping. Today Keith is sharing some insights into the world of Catfish, his favourite.
Keith Jackson is a retired engineer who has been keeping tropical
fish for 40 years and a pond for 11. His first love is the South American
family of small catfishes of the group Corydoradinae, covering the genera
Corydoras, Brochis, Scleromystax and Aspidoras.
From Keith's Corner:
I am a definite pisciphile but I really love to see catfish
moving around the bottom of a tank. A shoal of six or eight fish is a sight to
see and if the decide to spawn then that’s an absolute bonus. So I get very hot
under the collar when I hear people describe catfish as something you put into
a tank to keep the bottom clean as if they were natural Hoovers! With a few
exceptions, they are simply fish that have evolved to feed in the middle or
bottom of the water column. They were not put on this Earth so that lazy
fish-keepers don’t have to do as much maintenance!
Catfish, the Siluridae, are a very, very old group and are
found right across the world. They range in size from giants found in the River
Mekong (now possibly extinct) down to some really teeny species only an inch or
so long from South America. Some are carnivorous, some herbivorous and the
great majority are omnivorous. Some look cute as youngsters but are anything
but as adults. The Red Tailed Catfish look delightful at a couple of inches but
can reach around six feet and just one fish needs a tank of about 20,000
gallons to live in when fully grown. Yet you still see them for sale. Grrr!
Although not all catfish reach that size, there are still
traps for the unwary novice. Most tanks will develop algae on the glass. We
like to see our fish so we use artificial lighting, often designed to encourage
plant growth, and sunlight flashing off the flanks of a fish as it swims can be
a lovely sight. A shoal of a dozen Diamond Tetras in one of my tanks show
greens, golds and many other colours in the their reflective scales but I have
to clean the glass regularly or the algae takes over.
There are some natural remedies, such as shading the tank
from sunlight, reducing the time the lamps are switched on and changing the
water more often to reduce the amount of food available to the algae but many
fish-keepers go to their local shop for advice and are told “Get a
sucker-mouth.” The sucker-mouthed catfishes, sometimes wrongly called plecs,
are a large family from South America that are generally found in fast-moving
water. Some are herbivorous, a few can be described as opportunistic carnivores
but most are omnivorous. Most do not eat algae, despite their
reputation. Some do as juveniles but change diet as they mature. Quite a few
are ideal inhabitants for our tanks but some are not.
Bristlenoses are an interesting group that will make some
impression on algae but will need that to be supplemented with cucumber,
zucchini /courgette and specialist food tablets and there should be bog-wood in
the tank for them to chew on. They are readily available and quit easily bred.
Note: only males develop the characteristic bristles. They are usually black
with white spots or there is an albino for that is pink with yellow spots.
Beware, though, a plain brown fish with a large dorsal fin.
This is most likely to be Pterogoblicthys gibbiceps – aka the Gibby Plec – and
it gets much too big for anything under a six-foot tank. You will often see
them in display tanks at some aquatic outlets where their despairing owners
have brought them back because they’ve outgrown everything the owner has put
them into. Why do unscrupulous shop-keepers sell them? They’re dirt cheap
because they’re farmed for food so they offer a good mark-up. Money, that root
of all evil……
You are also likely to come across several species of
Corydoras catfish at most shops. They are almost all suited to tanks of two
feet/60 cm long and upwards and some species (C. pygmaeus; C. hastatus; C.
habrosus and C. cochui) barely reach one inch/ 25 mm so can be kept in shoals
in quite small tanks. In the wild, these fish live in huge shoals so they do
not show their true behaviour if kept in small numbers. They live quite a long
time and are generally hardy but they cannot defend themselves – they have no
teeth – and rely on their heavy rows of long scales, known as scutes, for
protection so you need to choose their companions with care.
You will see C. aeneus, the bronze cory, and C. palaeatus,
the spotted cory in most shops as they are bred by the thousand. They, like all
corys, should be alert and frequently disturbing the bottom on the lookout for
food. Their bodies should look robust and their stomachs should be flat, not
hollow. If they don’t look ‘right’, go elsewhere – which is the mantra for
every type of fish!
Suitability of water temperature is another thing most
people don’t associate with ‘tropical’ fish but can be important. Taking the
cory family again, you find them and their kin from the north of South American
down to Argentina. That far south some species live in stretches of water that
have ice on their banks! As examples, I keep Corydoras sterbai – quite a common
sight in shops – and that needs temperatures of at least 25 °C to spawn. I also
keep a less-common species, Corydoras nattereri, and that stops spawning
if the temperature rises over 23 °C.
The advice for catfish, as it should be for any type of
fish, is to do your research first. Nobody does that all the time and we all
end up buying something unsuitable from time to time but if we did that more
we’d have a lot less fish-keeping headaches!
