The Aquarists' Fish: The Headstander
By Dr David Ford, Consultant to Aquarian®, member of Halifax AS.

As Hans Baensch says in the 'Aquarium Atlas' - "Anyone who has not kept this fish cannot be called a true aquarist". He is referring to the most popular of all the Headstanders the Striped Anostomus, Anostomus anostomus. The reason is that this fish has all the attributes for survival in the home aquarium, but is still a challenge to keep and breed in captivity.

The fish lives in the rivers of the Amazonian Rainforest, in the fissures of rocky faces where it picks at the algae. It lives with large shoals, but will leave the group to forage for insects and worms to supplement the herbivorous diet.

This means it can live in a community aquarium as a lone specie, or be part of a large shoal in a theme tank. However, with rocky face living (just like many Rift Valley Cichlids) the fish can be territorial, so provide some slabs of rock for the fish to call home. Keep a shoal and they will group around this home, keep just a few (say a trio) then each will try to own the space and aggression follows.

Since the fish needs algae, a brightly lit aquarium is ideal. Live plants are not eaten, but the fish needs the broader leaf varieties where it can peck at algal growth. Water should be of medium hardness and slightly acidic, but it will accept ordinary (dechlorinated) tapwater. Hence, again, the fish will live in the aquarist's average tank, but to develop the fish's true colours the water chemistry must be controlled.

Those colours are superb - the fish is the most colourful of all the South American Characins with its zig-zag patterns, golden yellow stripes and blood red flashes in the tail.

Breeding is also a challenge with no records of aquarium spawning to date (unless any readers of this article have succeeded - let us know!).

My Experience

I have tried - and failed - to get the Anostomus to breed. It is claimed to be an egg scatterer and Killifish-style mops have been used. The fish probably breeds at depth in the wild, something that cannot be reproduced in the usual 15" (38cm) deep aquarium. For pairing there is little sexual difference, the males are just slightly slimmer. I never produced a female fat with eggs, despite an ideal diet and conditions.

That ideal diet was Aquarian® flake plus Spinach (baby food from a jar) and the occasional worm (clean, home-bred, live tubifex). On this food the fish grew to the maximum size (quite large - 5 inches/12cm) and lived several years, but there were no descendants to continue the trials in the Waltham® Aquacentre.

The Headstanders

Another special attraction of the Striped Anostomus is its peculiar swimming habit, with the head downwards - which, like Concorde, rises with speed! The fish also topples over as it grubs in the base sand (which is better than gravel for these fishes) for worms. This is because the mouth is upturned for algal grazing.

In fact there are a whole family group of these 'Headstanders' from the Amazon river. They all show the swimming or resting in the head down position and this gave them their name. This is a universal name too - the Spanish call the fishes 'pez verticales'.

They are all Characins with typical adipose fin and torpedo shape. All are from the Amazon basin (and are therefore called the American Characins) and, as usual, the common names are confusing. Because Anostomus anostomus is the most popular, this fish is often sold as the 'Headstander', but the true 'Headstander' is Abramites microcephalus, although sometimes the name is used for Chilodus punctatus - which is really the Spotted Headstander.

___________________________BOX_________________________________

Species Common Names Comments

Anostomus anostomus Striped Anostomus The most popular
Headstander

Abramites microcephalus Headstander Now renamed
High-back Headstander A. hypselonotus

Chilodus punctatus Headstander Like Anostomus
Spotted Headstander but more timid

Anostomus fasciatus Six-barred Anostomus Rare Anostomus

Anostomus gracilis Four-spot Anostomus Rare, but when
imported, usually
confused with the
three-spot

Anostomus trimaculatus Three-spot Anostomus Will eat soft plants

Anostomus taeniatus Banded Headstander American Indians
call this fish 'Lisa'
(actually the name
of the discoverer)

Anostomus ternetzi Anostomus Less colourful than
the Striped Anostomus
but more peaceful

There are other Headstanders but you do not see them in the aquarium trade being rare or too large (in fact some are caught as a food fish in the Amazon).

Why Stand on your Head?

The aquarium literature (nor the Ichthyological literature) offers any reason for the head-standing behaviour of the Anostomidae. However, when I carried out postmortem examinations of Anostomus anostomus that eventually died it was obvious that the swim bladder was further back than occurs in most fishes. Also, the bladder was thinner to the front and wide at the rear - hence the reason for the head-down posture. That doesn't explain why the fish has such a different swimbladder, but certainly gives a reason for the head-down - the tail has to go up!

The fishes are also Characins and so have the extra back fin (adipose), but there is no scientific reason for this fin. Some claim it is vestigial (an organ that has degenerated over millennia until useless) but others claim it gives added stability in water dynamics. Perhaps the head-down is a consequence of a vestigial shape swimbladder…however, fish such as A. anostomus can easily flip over and browse upside down or right way round to gather algae from crooks and crevices. This helps it survive in the wild, even if other foods are scarce, but does give delightful antics in the home aquarium.

Be a true aquarist - get a Headstander, or two, or a shoal.

Many Thanks to Dr David Ford,

http://www.drdavidford.pwp.blueyonder.co.uk/

.