WARNING: Do not add salt directly to your tank if you are using a zeolite filter media. You will want to use a hospital tank instead. I will not convert weight in grams into tablespoons as it’s best that you weigh it.
Some fish infections are dangerous to humans and other animals, especially immune compromised humans. Always wash your hands well after touching your aquarium water and fish.
Bloating in the abdomen: If your fish is bloated in the abdomen (right behind the pectoral fins and right over the egg spot in females), it has either overeaten or if it’s a female it could have built up a good collection of eggs. Fasting is the cure for both of these. Do not feed your fish for three days. If you have access to daphnia (water fleas), these can help as a mild laxative. As a last resort, five minute epsom salt (magnesium sulphate without any fragrances or other additives) dips (30 grams of epsom salt and 7 grams of regular salt per 10 liters of water) can help them poop. When making a bath or dip, use aquarium water. If you will be reusing it, I recommend a specimen container that floats on top of the aquarium to keep the water at the same temperature as the tank.
Bloating in other places: If your fish is bloated in places other than the abdomen, your fish has gained some water and now has what’s called edema or osmotic stress. If it gets real bad, their scales will lift up and people call this pineconing and dropsy but the technical term is osmotic shock. The cure for this is salt (NaCl). Regular seasalt from your kitchen is fine. Even iodized salt is fine if it’s all you have. Do not use water softener salt as it contains other agents. Use 5 grams of salt per liter and add directly to the tank unless you have a zeolite filter. Salt can also kill snails and some live plants. If you can’t treat the tank, try putting him or her in a heated hospital tank with water from the tank. Fish have a low survival rate.
Red streaks: If your fish has red streaks, it has a serious infection known as septicemia. The best medicine for this is Seachem Kanaplex using its oral dosage instructions. Basically add one level measure (it comes with a measuring spoon on the lid) to one tablespoon of food. Feed the fish once every two days up to three times. Keep left over food in the fridge. Fish have a low survival rate.
Ich: If your fish is getting covered in white or yellow spots that look like grains of salt, it has ich. Bring the salt level up to 1% (add 10 grams of salt per liter). Heat the tank up to 86 Fahrenheit (30 Celsius). Do a 30% water change daily and try to vacuum up the waste protozoans from the bottom of the tank while doing so. Fish have about a 50% survival rate with this treatment. If this sounds too hard, you can add Malachite Green (most of the ich treatments at the pet store). Just follow the instructions, but your fish will only have a 9% chance of survival, which is only 1% better than doing nothing.
Pop-eye (popeye): When one eye is protruding more than the other, which often leads to both eyes protruding, your fish has pop-eye (Exophthalmia). Treat with API Fin & Body Cure. The antibiotic in this product is light sensitive. Please cover your aquarium in a blanket or something similar to prevent it becoming inactive.