This so infuriating. Now I have 2/6 forktail rainbowfish left. 3 more died today after a small 2 gallon water change in my 10g quarantine tank. I've probably had 30+ fish so far this year with ~10 surviving. Not sure how you all deal with it but fish keeping is just too stressful for me and doesn't seem worth it at this point.
Start a new thread asking for help with sick fish or post info here about them.
Post pictures and video of the fish. Upload videos to YouTube then copy & paste the link here.
If fish die straight after a water change, it's usually chlorine/ chloramine poisoning. Double dose the aquarium with dechlorinater and increase aeration/ surface turbulence. Rainbowfish are sensitive to chemicals.
Make sure you dechlorinate tap water before adding it to the aquarium.
If rainbowfish get sick add salt. See directions below.
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SALT
You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres (5 gallons) of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.
Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, Bettas & gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.
The salt will not affect the beneficial filter bacteria, fish, plants, shrimp or snails.
After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.
If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.
When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.
