Before you use any medication on your tank be sure to properly diagnose the fish disease and try to figure out why your tropical fish have the disease. Many diseases are brought on by the tropical fish being stressed due to transport or water quality issues. If you've just set up your tank, please read about new tank syndrome.
It's a very good idea to have a small quarantine tank for new fish so that you may monitor the fish for a few weeks before adding the fish to your main tank. You can also use the quarantine tank for your fish that come down with a disease and can avoid adding chemicals to your main tank. Always practice good fish acclimation techniques and don't rush things.
Try to determine the underlying problem before medicating. Often times there are water quality issues that need to be remedied first. Get and use an aquarium test kit and take the appropriate measures to correct the water in your aquarium.
Whenever you use any type of medication on your tropical fish, first remove any carbon in your filtration system. If left in, the carbon will remove the medication from the water, doing you no good. Read the directions on the medication bottle very carefully!
To sum up, first determine the cause of the freshwater fish disease, fix any obvious problem(s) (water quality problems and/or tank mates), figure out which disease your fish has by closely observing the symptoms and then treat if necessary.
| Disease / Problem | Symptoms | Treatment |
| Ammonia Poisoning | Red or inflamed gills. Fish are gasping for air at the surface. New tank setup or a tank with too many fish. | Ammonia poisoning is easily preventable. Avoid adding expensive and less hardy tropical fish until the aquarium has cycled. For more information on cycling your aquarium please read about the aquarium nitrogen cycle you can use a substance called zeolite to help absorb ammonia but the best solution is to ensure that your aquarium has cycled and that your tank is not overcrowded. If your tank has not yet completed the nitrogen cycle, you will need to perform frequent water changes to keep the ammonia levels down. |
| Dropsy or Malawi Bloat | Bloated fish, scales are raised, possible loss or lessening of body coloration. | This is not really a disease, but a symptom of a bacterial infection and possibly malnutrition. There are medications available but try to increase the quality of the water by performing a 25% water change every other day and increase the quality of fish food given. If your fish's condition doesn't improve, try the medication. Your local pet store should have medication for this disease. Remove any carbon filtration before using medication because the carbon will remove the medication from the water. |
| Ich, Ick or White Spot (Ichthyophtirius) | Small white spots showing up mainly on the fins but also on the body. It looks like your tropical fish has salt all over it. More information on Ich | This is a fairly common fish disease and your local pet store should have medication you can use. Ich usually arises due to poor water quality. You can increase the temperature of your water to 82 degrees Fahrenheit to speed up the cycle time of this parasite. Remove any carbon filtration before using medication because the carbon will absorb the medication. Easily preventable by using a quarantine tank for a few weeks before introducing new arrivals into your main tank. |
| Fin Rot | Rotting fins, loss of appetite and laying on the bottom of the tank. This is due to a bacteria that infects the fins of the fish. It is sometimes brought about by bullying from other fish and fin nipping. Most often it is due to poor water quality. | There are medications available such as Tetracycline from Mardel Labs. Remove any carbon filtration before using medication because the carbon will absorb the medication. Before using medication though try increasing the quality of the foods you are feeding your fish, separate them from any fin nippers and step up your water change schedule. More information on Fish Fin Rot |
| Fish Fungus | Cotton like growths on the body that may appear white or gray in color. | Be sure to give your fish the best water you can by performing frequent water changes. If your fish gets a disease they may develop secondary fungus infections. Medications such as Jungle Labs Binox Crystal will treat fungus problems. More information on Fish Fungus |
| Hole in the Head - HITH, sometimes referred to as Head and Lateral Line Erosion - HLLE | Small holes or indentations on the head of fish, advanced cases may show markings along the lateral line of the fish. They may stop eating. | There are many theories out there, but no conclusive scientific evidence as to what exactly causes this disease. However, it may be attributed to poor water quality, lack of proper nutrition and/or the use of activated carbon for prolonged periods. However, there have been no scientific studies about the effects of the prolonged use activate carbon causing hole in the head, it's just speculation. Be sure to give your fish the best water that you can by performing frequent water changes. Give them vitamin enriched foods and change out or stop using activated carbon. |
| Nitrite/Nitrate Poisoning | Tropical fish are lethargic or resting just below the water surface and you are getting high readings on your nitrite and nitrate test kits. | Nitrite / Nitrate poisoning is not a disease but will kill your tropical fish if not remedied. It results from having a large bio-load on the filtration system or from not performing enough water changes. Perform a partial water change immediately and monitor the nitrite and nitrate levels closely until the situation is resolved. You may have too many fish in the tank and will need to perform more frequent water changes. Nitrite readings on your aquarium water test kit would indicate that your tank is still in the aquarium nitrogen cycle nitrite phase, or it is undergoing a mini-cycle if you've recently added more fish to the tank. |
| Oxygen Starvation | Most or all of the fish are usually found at the water surface. They may be gulping at the surface with their mouths. | Check the temperature of the water. Higher water temperatures require higher levels of oxygen. You will need to increase the aeration in the tank with airstones and/or powerheads and increase the flow rate with your filters. Try to decrease the temperature of the water by floating ice cubes in plastic baggies and turning off the tank light. If sun light is entering the tank from a nearby window, try closing the shades. Also, if you have an overcrowded aquarium you will definitely need to increase the aeration in your tank. |
| Pop-Eye | One or both eyes appear to be, protruding abnormally, "popping" or sticking out. | This is usually the result of a bacterial infection. Try to give your fish the best water possible by performing frequent water changes. To treat this problem you can use a treatment such as Tetracycline from Mardel Labs. If possible, increase the quality of food given. Supplement with vitamin enriched foods. More information on Fish Pop-Eye |
| Swim Bladder Disease | Fish have a difficult time staying upright and may hang in the water. Goldfish are especially prone to problems with the swim bladder. | Some hobbyists feed their fish peas to treat this infection. Perhaps this works by helping in the digestion process. Try this: stop feeding the fish for a few days, give the fish optimal water conditions by performing frequent small water changes (10% every week) and see if the problem clears up. |
| Velvet (Oodinium) | Velvet looks a lot like ich but velvet shows up as smaller yellow or gray dusty spots on the fish. Tropical fish with velvet will have rapid gill movement and may be rubbing on surfaces in the tank. | There are a lot of products out there to treat this common tropical fish parasite. For example, Aquarisol works on ich and velvet. This is easily preventable by using a quarantine tank before introducing new arrivals into your main tank. |