Aquarium help - All the information you need to create and maintain a beautiful aquarium
How can you diagnose fish disease?
The first point to make is that behavioral and physical changes are a really useful sign that something is wrong, but many of these changes can be caused by more than one disease condition.
In general, most fish disease is down to poor water quality, and in general, is very difficult to diagnose.
This page is not intended to provide you with a full run down of all possible diseases that can affect your fish. It is intended instead at providing you with a quick reference guide to help you treat some of the more common ailments.
The key to a healthy aquarium is, of course, regular and correct maintenance. In almost all cases of fish disease, your fist step should always be to check your water quality.
Poor water quality is the cause of most fish disease, so if you notice physical and/ or behavioral changes in your fish, your first course of action should always be to check your water quality and clean your aquarium.
Check for nitrates, nitrates and ammonia.
- If any of the levels are very high, then you may need any emergency chemical treatment, but if they are just a little
high, change between 10 and 35% of the water in your aquarium.
- Make sure you remove any dead or dying organic matter from your aquarium. You can purchase an inexpensive
suction cleaner that will syphon water from your tank, and with a little effort, bring with it all the organic material
from the bottom.
Check also for dissolved oxygen.
- If levels are too low, ensure your water is moving and the surface disturbed.
A small air pump connected to an airstone is a good way to do this.
Add oxygenating plants.
Ensure your tank is not overstocked.
Ensure your filter is working.
- Ensure your mechanical filter (the bit that traps larger particles from your water, that will usually be a plastic mesh
of some kind) is cleaned thoroughly.
In the section below, we discuss some of the more common symptoms, the likely causes, and some possible treatments.
Several of your fish die at more or less the same time.
Survivors hang around the water surface or stay on the bottom and may lose equilibrium.
They are lethargic and don't eat.
1. Poisoning
2. Water Quality
3. Lack of Dissolved Oxygen
4. Severe Bacterial Infection
Possible Cause
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
If you suspect poisoning, change up to 75% of the water.
2. Check dissolved oxygen levels, and if necessary, take steps
to increase the levels.
3. Unfortunately, if your fish are suffereing a severe bacterial
infection, there is little you can do.
If your fish are particularly valuable, you may want to consult
a vet, but the costs make this impractical for most people.
Possible treatment
Your fish rub against solid objects in the tank, and when they turn to rub their sides, their underside flashes silver as the light catches.
They may leap out of the water.
1. Water Quality
2. Parasites
3. Infection
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Parasites such as flukes, Trichodina, white-spot etc on the
skin or gills can cause irritation, but can be extremely
difficult to spot.
If symptoms persist after you have cleaned the tank and
changed the water, it is a sensible precaution to treat the
water with a medicine available from your pet shop
Your fish swim normally but seem to be gasping for breath
1. Water Quality
2. Low levels of dissolved oxygen
3. Gill Disease
4. Gill Parasites
5. Anaemia
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
If you suspect poisoning, change up to 75% of the water.
2. Check dissolved oxygen levels, and if necessary, take steps
to increase the levels.
3. If water quality and dissolved oxygen levels are OK, treat
your water will a medicine available from your pet shop.
4. Gill parasites can be virtually impossible to spot.
If symptoms persist after steps 1, 2 and 3 in this section, it
is a sensible to treat the water with a parasite treatment
available from your pet shop
5. If your fishes gills look pale, treatthe water with an
anemia remedy available from your pet shop
Individual fish become isolated.
They breath normally, but may refuse food.
There could be grey or "cloudy" areas on the skin.
1. Water Quality
2. Parasites
3. Infection
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Parasites can be extremely difficult to spot.
If symptoms persist after you have cleaned the tank and
changed the water, it is a sensible precaution to treat the
water with a medicine available from your pet shop
Your fish are lethargic and are eating very little if anything.
They may be nervous, shy & skittish and may also have ragged fins.
1. Water Quality
2. Organic pollution
3. Parasites
4. Infection
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Remove as much organic waste as possible from your
aquarium.
3. If dissolved oxygen levels and water quality are OK, then
treat your water with a general medicine available from your
pet shop.
4. Parasites can be very difficult to spot.
Treat your water with a medicine available from your pet
shop.
Your fish produce too much gill or skin mucus resulting in Grey slime/ trailing mucus.
1. Water Quality
2. Parasites
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Parasites can be very difficult to spot.
Treat your water with a medicine available from your pet
shop.
Your fish have skin lesions or ulcers with red inflamed patches on their fins or body.
There may be raised scales andlocalised swelling.
1. Water Quality
2. Parasites
3. Physical damage
4. Organic pollution
5. Bacterial disease
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Parasites can be very difficult to spot.
Treat your water with a medicine available from your pet
shop.
3. Severe physical damage can best be treated by isolating the
fish in a separate tank, giving it time to recover
4. Remove as much organic waste as possible from your
aquarium.
Your fish have red lesions.
1. Water Quality
2. Parasites
3. Physical damage
4. Overcrowding
5. Bacterial disease
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Parasites can be very difficult to spot.
Treat your water with a medicine available from your pet
shop.
3. Severe physical damage can best be treated by isolating the
fish in a separate tank, giving it time to recover
4. If all else fails, treat your water with a general purpose
treatment available from your pet shop.
Your fish have white lesions.
1. Water Quality
2. Parasites
3. Fungal disease (including mouth
fungus, or cotton wool disease)
4. Overcrowding
5. Bacterial disease
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Parasites can be very difficult to spot.
Treat your water with a medicine available from your pet
shop.
3. If you suspect fungal disease, treat your water with a
specialist medicine available from your pet shop
4. If all else fails, treat your water with a general purpose
treatment available from your pet shop.
Your fish has dropsy - a swollen abdomen, and perhaps some raised scales, and slight reddening
.
1. Water Quality
2. Parasites
3. Viral disease
4. Neoplasm (tumour)
5. Bacterial disease (systemic)
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Parasites can be very difficult to spot.
Treat your water with a medicine available from your pet
shop.
3. Treat your water with a general purpose treatment available
from your pet shop.
4. Cross your fingers and hope it's not one of the more serious
conditions, although if it is, it is likely only to affect the fish
showing symptoms and is unlikely to spread
Your fish in unable to stay upright.
In some cases, it will be able to maintain position when swimming but will turn over as soon as it stops
.
1. Water Quality
2. Swim bladded disease
3. Infection
4. Organ disease
5. Constipation
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Parasites can be very difficult to spot.
Treat your water with a medicine available from your pet
shop.
3. Treat your water with a general purpose treatment available
from your pet shop.
Your fish has tiny white spots on skin and fins as if it's been sprinkled with salt.
1. Water Quality
2. White Spot disease
1, Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Treat your water with a specialist white spot treatment
available from your pet shop.
White or or discoloured 'cotton-wool' patches on the skin or fins
1. Water Quality
2. Fungus disease
1. Test your water and change up to 25%
Clean your tank and filter thoroughly.
2. Treat your water with a specialist fungal treatment available
from your pet shop.
Your fish has a cloudy eye
1. Water Quality
2. Nutritional deficiency
3. Infection
1. Tst your water and change up to 25%
Clean your tank and filter thoroughly.
2. Treat your water with a general purpose treatment available
from your pet shop.
