How to Check Your Fish for Parasites

If you suspect something is wrong with your fish, it might be a parasite. Check for the following symptoms to diagnose the problem.

Difficulty:

Easy

Instructions

1. Check for visible parasites such as worms or leeches, or flukes on the fish's body.

2. Remove parasites manually from the fish; follow-up treatment is vital to prevent bacterial or fungal growth.

3. Examine your saltwater fish for prominent ulcers and holes on the fish's body that might be flukes.

4. Look to see if your fish has cloudy eyes, white patches or is gasping for air, rubbing on objects and is listless. These symptoms could be caused by fish lice.

5. Internal parasites will cause loss of appetite, listlessness and erratic swimming.

6. Note redness, irritation and/or threadlike worms coming from the fish's tail area. If accompanied by bloating, these symptoms indicate a nematode infestation, also known as roundworm. Nematodes live in the intestines and should be treated carefully.

7. Notice if the fish has pinhead-sized white dots on its skin and fins or gills, or looks like it was dusted with salt. Or, it may quit eating, start hiding abnormally, rub and scratch on objects or breathe at the surface. The fins will be folded back (clamped), and the eyes might be cloudy. If it has these symptoms, suspect white spot or ick (ichtyophthirius).

8. Look for small white or gold speckles resembling powder on the fish. This could be velvet, or oodinium, a common disease that resembles ick. The pustules are much smaller and are typically located on the body. The fins may be clamped tight to the body and the fish may seem unstable when it swims.

Tips & Warnings

• White spot or "ick" is a very infectious disease, and is usually introduced to the aquarium with new plants, fish or live food. It's caused by a protozoan that grows on a fish, falls off and attaches to the gravel or tank walls and then reproduces heartily. Ick is the most common freshwater fish disease. Saltwater fish can also get black ick, with black spots.