Home > Tips > How To Detect Fish Diseases And Injuries

How To Detect Fish Diseases And Injuries

By: Jennie Kermode - Updated: 17 Sep 2015 | comments*Discuss
Tropical Fish Fish Diseases Aquarium

Every aquarist fears disease and no matter how well you care for your tropical fish, it's always a risk. Fortunately, the majority of fish diseases which affect aquarium fish can be effectively treated. The difficult thing is spotting them in time. The sooner you know a fish is ill, the better the chance that you can save it and that you can prevent the infection from spreading to others.

It's easy to tell that something is wrong with a tropical fish when it has open sores, ragged fins, or woolly-looking fungus on its skin, but by then it's often too late for effective treatment, and at best your fish is going to be left with long-term injuries. But there are several things you can do to detect fish diseases at an earlier stage, so that you're ready to act as soon as physical symptoms occur to confirm it.

Trust Your Fish

The best way to find out when something is wrong with your fish is to let them tell you. Fish who are feeling under the weather won't behave the same way as they do when healthy – any more than you would. What's more, other fish won't treat them the same way.

When you see a fish that is normally active start to slow down and behave in a listless, uncertain way, it's a good bet that it has a tropical fish disease. You should also be suspicious if a fish stops eating properly, spends a lot of time resting on the bottom of the fish tank, or starts hiding away more than usual. Sick fish lose energy and confidence. They'll stop using assertive body language – for instance, most species will lower the dorsal fin and let the tail hang limp. They'll back off when challenged by other fish.

As well as body language, the other fish in your aquarium have further clues to go on. Sharing the same water, they'll notice when an individual's scent changes. Because of this, they'll almost always be aware of a fish disease before you are. Occasionally, especially where there is a strong pair bond, fish will try to help a sick individual (perhaps helping it around or bringing it food), but more often their natural fear of becoming infected themselves will lead to them shunning that individual or even trying to drive it away. This can lead to aggressive chasing. If a tropical fish that has previously fitted in well suddenly becomes the target of bullying, it's time to check for signs of disease.

Physical Changes In The Fish Due To Fish Disease

We sometimes refer to people who are ill as being 'off-colour'. This is literally true with many tropical fish. It takes energy to maintain bright colours and sick fish are liable to fade. They'll certainly stop displaying socially or sexually assertive colours as strongly as usual. In some cases, however, internal bacterial infections can actually cause a fish's colour to darken, so any kind of colour change should make you suspicious. You should also look out for small dark patches or reddening, which may indicate bruising. Of course, bruises can be caused by accidents or skirmishes with other fish in the fish tank, but they can also be a result of skin infections or internal haemorrhaging.

Healthy fish should have bright, clear eyes. If the eyes become cloudy or swollen, or if the fish does not appear to be focusing properly, something is wrong. Most fish should have no difficulty following the line of your finger as it moves across the glass. If they appear unable to do so, you should check for other signs of illness.

Swelling of any part of a fish's body should be cause for concern. It can happen as a result of injury, but if that's the case you should see it start to subside after a day or two. Sometimes swelling can start with injury but persist due to infection of the wound, in which case you should be ready to deliver appropriate treatment. Persistent swelling of the abdomen in the tropical fish, if not due to the production of eggs, is particularly worrying, as it can be a sign of serious internal damage. If this happens, try adjusting your fish's diet, but keep a close eye out for any sign of deterioration.

The key to good aquarium management is paying close attention. This is never truer than in the case of fish disease. Though there's no guarantee that you'll always be successful, you can keep your tropical fish a lot safer by being ready to detect disease the moment it appears. Contrary to many people's opinion, there is no reason why fish should suffer from tropical fish disease on a frequent basis. With good care, your tropical fish should be able to lead long, healthy lives, bringing you a great deal of happiness.

You might also like...
Share Your Story, Join the Discussion or Seek Advice..
It is hard to tell without seeing your fish. However, there is obviously something wrong and that could stem from disease or something is amiss tank management. You need to seek some advice very soon before you lose any more!
Cal - 18-Sep-15 @ 11:51 AM
I have had unexplained death in four fish over the last month the fish look normal but stop feeding and die iv just noticed my simese fighter now looks pale and bloated he is feeding but doesn't look right to me
christine lewis - 17-Sep-15 @ 9:08 AM
Share Your Story, Join the Discussion or Seek Advice...
(never shown)
(never shown)
(never shown)
(never shown)
Enter word:
Latest Comments
  • Fishlife
    Re: Dealing with Bullying Between Fish
    If they are the same fish and one of the fins look eatin on what do i do? Im getting nervous because i nevee see them…
    20 May 2018
  • Fishyowner
    Re: Caring for Baby Fish
    Is it ok to put a tiny adult fish in with a baby fish?
    5 April 2018
  • Tee
    Re: Why do my Fish Keep Dying?
    Can 3 female platies, 5 female neon tetras, and a nerite snail live together as tank mates in a 10 gallon take and all be safe?
    26 March 2018
  • Dick
    Re: Tank Cleaner
    Re: tropical fish tank, 30 gal, no live plants. Filter change each 30 days, remove items in tank and gravel clean each 45 to 60 days. I have 3…
    19 February 2018
  • RoB
    Re: Dealing with Bullying Between Fish
    @Shaunaa - separate them again. The dominant fish is obviously bullying the other fish as it's probably not up to being…
    8 February 2018
  • Shaunaa
    Re: Dealing with Bullying Between Fish
    I have two fish a very long time but one got sick so I had to separate them for a while now I have put him back into the…
    7 February 2018
  • Plane jane
    Re: Dealing with Bullying Between Fish
    Have recently bought cichlids at Xmas +1 was bullying other's. I had 2 larger + 2smaller. Introduced 2more large +2more…
    19 January 2018
  • Gwenba
    Re: Dealing with Bullying Between Fish
    I have 2 large parrot fish one seems to Be bullying the other is this common
    11 January 2018
  • Andrea
    Re: Dealing with Bullying Between Fish
    My guppy fish is quite old and before I was observing them and I saw a my phantom fish bite it on his tail vigorously.…
    27 December 2017
  • Ana
    Re: Aquarium Medicine Cabinet
    Hi there , can tcp treat white spots and the tank itself. ....??? Thanku
    24 December 2017
Further Reading...
Our Most Popular...
Add to my Yahoo!
Add to Google
Stumble this
Add to Twitter
Add To Facebook
RSS feed
You should seek independent professional advice before acting upon any information on the TropicalFishExpert website. Please read our Disclaimer.