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.
is also a challenge with no records of aquarium spawning to date (unless any readers
of this article have succeeded - let us know!).
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
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
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'.
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.
Common Names Comments
Anostomus anostomus Striped Anostomus The most popular
Abramites microcephalus Headstander Now renamed
Headstander A. hypselonotus
Chilodus punctatus Headstander Like Anostomus
Spotted Headstander but more timid
Anostomus fasciatus Six-barred Anostomus
Anostomus gracilis Four-spot Anostomus Rare, but when
confused with the
Three-spot Anostomus Will eat soft plants
Anostomus taeniatus Banded Headstander
call this fish 'Lisa'
(actually the name
Anostomus ternetzi Anostomus Less colourful than
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?
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!
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
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