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Self-Improvement & Hobbies

Sick fish

Learn to read these telltale signs of illness before you treat your fish
CATS Classified In The Straits Times - September 4, 2010
By: Wong Wei Chen
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Sick fish

It’s been quite a while since I last broached the subject of illness, that unpleasant topic that nobody really likes to talk about. In fact, I was recently afflicted with a rather severe bout of diarrhoea, but I’d rather not talk about it. (See what I mean?)

I suppose some veterinarians specialise in treating fish, but by and large, when our aquatic pets fall sick, most amateur aquarists have two options. You can choose to ignore the fish, and leave it to its own devices. (Don’t be surprised by this, but there are aquarium owners who think nothing of fish dying. It’s just a matter of replacing dead fish to them.)

Alternatively, you can try to diagnose the problem, and take steps to rectify the situation. (Now, that’s more like it.)

For starters, let’s learn to spot signs of sickness; before you can treat your fish, you need to know when it’s sick, right?

How do you know when your fish is sick?
Sick fish often exhibit one or more of the following symptoms:

Clamped fins
Fish which display this symptom have their fins held abnormally close to their bodies. However, do note that some species clamp up their fins while swimming, so don’t jump the gun and start pumping medication into your tank. Only when you observe clamped fins even when the fish is stationary should you take action.

Loss of appetite
Pay attention when your fish deviates from its normal feeding routine and refuses to eat. For many species, constant foraging and eating is the norm, since such behaviour maximises their chances of survival in the wild. So if a glutton were to stop eating, that’s a bad sign.

Blemished skin

Spots, lesions or white patches spell trouble, and these could be accompanied by abnormal behaviour such as constant scratching against plants, rocks or aquarium decorations.

Respiratory problems

Fish exhibiting this symptom will be seen gasping at the water surface. Make sure, however, that this is not caused by inadequate aeration in your aquarium. A decent tank ought to at least have a mechanical filter that will ruffle the water surface through its filtering action, since such disturbance will help atmospheric oxygen dissolve in the water. Many aquarists will in fact include an additional air pump.            

Bloated body

A bloated fish with protruding scales may be afflicted with dropsy. Dropsy is a generic term for several kinds of disease that make a fish’s abdomen swell unnaturally. Causes could include cancer in internal organs or the presence of large parasites.

Odd swimming position

A fish that tilts while swimming, or sinks or floats to the surface may be suffering from swim-bladder disorder. A swim bladder is an organ that acts somewhat like a balloon, which the fish can inflate or deflate to rise or sink through the water.

Antisocial behaviour

Like us, sick fish tend to be antisocial. If you see an otherwise gregarious fish hide behind plants, or isolate itself in a far corner of the tank, even when it’s feeding time – you can be sure that it’s unwell, and not just for this reason alone. It’s feeding time, but it’s not eating! (See symptom 2 above.)


Bacterial diseases