Livebearer white tail disease?

Hi all,
After a few years I decided to convert my 30 gallon gourami tank into a livebearer community tank. I re-homed the last surviving gourami and added 4 platys, 9 guppies and 8 tetra. Stupidly I didn’t quarantine in any way and now regretting it (I’m not an experienced fish keeper I’ve only ever had this tank). After a week I noticed callumanus in one of the guppies that died quickly as I started treatment on the tank.

The next day one of the platys developed a strange white skin around the base of the tail (doesn’t look like a fungus, more like a snakeskin shedding?). The tail fin was also rotting. This platy died within 24hr and the tail was completely rotted away. Today one of the male guppies has the exact same symptoms and I’m worried this will simply work through the whole community. I’ve done a lot of searching but can’t pinpoint any advice that matches this exact symptom so not sure how to approach to quickly save them.

I’ve attached a couple of photos of the guppy. It’s clearly fatigued and sticking to one spot in the tank without moving much. Please help!

It's excess mucous caused by something in the water irritating the fish. Because it's only in one patch its most likely a bacterial or protozoan infection.

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Check the water quality for ammonia, nitrite, nitrate and pH.

Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.

Do a 75% water change and gravel clean the substrate. The water change and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.

Increase surface turbulence/ aeration to maximise the dissolved oxygen in the water.

Add some 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 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.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 2 heaped tablespoons per 20 litres and if there is no improvement after 48 hours, then increase it so there is a total of 4 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 but the higher dose rate (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate (1-2 heaped tablespoons per 20 litres) will not affect 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.

Thanks Colin,
The guppy has died this morning so quite worrying for the rest of the fish.

I regularly use test strips to check the parameters and it always seems fine. I also do 10-20% water changes every 2-3 weeks. The tank has a large canister filter which is probably overkill hence the less frequent water changes. The only thing I can think off is chlorine creeping up but again the test strips never pick it up.

Racking my brain for what could cause the irritation but I’ll follow the instructions in your reply.

Chlorine should not creep up. It is in tap water and if dechlorinator is used before putting it in the tank that will remove all the chlorine. It cannot creep up unless undechlorinated water is added.

Most of us do 50% water changes every week.

dxniel said:

Hi all,
After a few years I decided to convert my 30 gallon gourami tank into a livebearer community tank. I re-homed the last surviving gourami and added 4 platys, 9 guppies and 8 tetra. Stupidly I didn’t quarantine in any way and now regretting it (I’m not an experienced fish keeper I’ve only ever had this tank). After a week I noticed callumanus in one of the guppies that died quickly as I started treatment on the tank.

The next day one of the platys developed a strange white skin around the base of the tail (doesn’t look like a fungus, more like a snakeskin shedding?). The tail fin was also rotting. This platy died within 24hr and the tail was completely rotted away. Today one of the male guppies has the exact same symptoms and I’m worried this will simply work through the whole community. I’ve done a lot of searching but can’t pinpoint any advice that matches this exact symptom so not sure how to approach to quickly save them.

I’ve attached a couple of photos of the guppy. It’s clearly fatigued and sticking to one spot in the tank without moving much. Please help!

Click to expand...

Hello. That's a lot of fish to put into such a small tank all at once. Most, if not all tank problems are due to poor water conditions. Clean up the water with larger, more frequent water changes and the health of your fish will improve.

10 Tanks (Now 11)