Tropical Community Tanks
1. Tank quite new, but lots of fish are dying!
Almost certainly down to poor water quality. The
biological filter takes about four to six
weeks to mature. While you can speed this up in various ways, it is
still easy to overstock/overfeed and end up with poor water
quality.
Use an ammonia or nitrite test kit to check water quality. Do lots of water changes; this will dilute the nitrite and
ammonia, helping the fish to recover.
2. Tank is mature, but lots of fish suddenly dying
There are three likely causes: poor water quality, rapid
changes in water chemistry, or the accidental poisoning of the water.
It is relatively rare for a killer disease to suddenly spring out of nowhere, though if you
recently introduced some new fish, they can certainly have brought
diseases with them (which is why you should quarantine new livestock).
Use an ammonia or nitrite test kit to check water quality. Are you are feeding the fish? Is filtration is adequate? Is the tank overstocked? Are you doing enough water changes? Most community fish are adaptable in
terms of water chemistry, but use a pH test kit to ensure water chemistry stays stable. If necessary,
incorporate chemical buffers to maintain
pH. Possible poisons include pesticides,
paint fumes, and other such chemicals.
Small
tanks (37 litres/10 gallons or less) are difficult to maintain and
easily overstocked. Water quality and water chemistry will fluctuate
quickly in these systems, stressing your livestock. If you have a small
tank, upgrading to one above 70 litres/20 gallons in size will
dramatically improve your hobby (as well as the lives of your
fish).
3. Some of my fish are sick
The vast majority of times fish get sick, the disease
involved is whitespot, velvet, finrot, fungus, or the shimmies. Use this article to establish which
disease is causing your problems, and then select the appropriate treatment.
Note that most of the WWM crew aren't wild about tea tree oil products
such as Melafix and Pimafix. At best these are unreliable cures, at
worst completely useless. There are ample, medically-tested products
out there: use those instead.
4. Livebearers (Mollies, Guppies, etc.) sick
All Central American livebearers need hard, basic water. If kept in
soft, acidic conditions they are prone to diseases such as finrot. Mollies are additionally very sensitive to
nitrate, particularly if kept in freshwater rather than brackish or
marine conditions. Mollies are therefore most easily maintained (and
some would say only ever reliably maintained) in brackish water with at
least 3-6 grammes of marine salt mix per litre (SG 1.003-1.005).
Because Mollies, and to some degree livebearers generally, have very
particular water chemistry requirements, they are best maintained in
their own aquarium rather than a standard community system.
5. Neons dying one at a time; everything else is the
tank is fine
Neon tetras are prone to a disease known as Pleistophora hyphessobryconis or Neon
Tetra Disease (NTD). The symptoms start with shyness and loss of
appetite, the infected neon usually leaving the school and hiding in a
dark corner. Gradually the colours fade to off-white, the fish becomes
lethargic, either bloated or emaciated, and then dies. There's no cure. The best you can do is
isolate infected fish to prevent infection of healthy fish. Observe the
fish carefully, and if the symptoms match NTD, painlessly destroy the
fish. Pleistophora can infect species other than neons, though
infrequently.
Neons can of course become sick because of other things
such as finrot and fungus, so simply because you have a sick neon,
don't automatically assume it's Neon Tetra Disease.
6. Dwarf Gouramis are becoming emaciated, losing their
colour
Dwarf gouramis are prone to a virus known as the Dwarf Gourami Iridovirus. One study by vets found
that 22% of the dwarf gouramis exported from Singapore were infected
with the virus. Infected fish gradually weaken and lose their colour,
eventually developing sores and lesions on the body. The faeces become
stringy and pale. The virus appears to be 100% fatal and completely incurable; it is also highly
infectious. Sick fish should be isolated at once, and if Dwarf Gourami
Disease is confirmed by careful observation of the symptoms, the fish
should be painlessly destroyed.
Dwarf Gouramis may become sick for a variety of other
reasons, and diseases like finrot and fungus can create superficially
similar symptoms. That said, the quality of dwarf gouramis on the
market is very variable, so take great
care when shopping for these fish. Ideally avoid them altogether and
opt for hardier, easier to maintain species such as Colisa
fasciata and Colisa labiosus.
7. Fin-nipping, or some of your fish have ragged
fins
Ragged fins can be a symptom of finrot, but if your aquarium enjoys good water
quality and the fish seem to have had bites taken out of their fin
membranes, fin-nipping may be a problem. Multiple so-called community
tank species are known to be fin-nippers and should never be kept with
slow-moving or long-finned species (such as angelfish and guppies).
Among the most common fin-nipping fish are various (though not all) Hyphessobrycon spp.
(most notoriously serpae tetras and jewel tetras); Gymnocorymbus ternetzi (also known as
petticoat tetras, black tetras, and black widows); and Puntius tetrazona (also known as
tiger barbs).
8. Snails everywhere!
Snails turn uneaten food and
other wastes into baby snails. If you have problems with snails, then
the first step in fixing things is to establish what they're
eating. Avoid using snail-killing potions: having lots of dead snails
rotting in your aquarium will reduce water quality dramatically. There
aren't any completely community-tank safe fish that eat snails,
though loaches and thorny catfish (family Doradidae) will eat snails if
they are sufficiently hungry. But do be aware that loaches are
gregarious and often boisterous fish, and thorny catfish will also eat
very small fish including neons. |
