Strange lump on my red rainbow anyone help?

[Josh92]

Can anyone help me I bought this red rainbow today, the chap serving me managed to drop the fish on the floor he was the last one tho and really wanted him so he said he’s guarantee it for me , I’ve got Him home he seems to have some sort of lump or growth in his side , does anyone know what this might be? If so what should I do , I’m able to return him tomorrow if needs be but I’d rather not.
Any help much appreciated
I’ve attached some pictures for you

 

[Colin_T]

It's possibly damage from being dropped on the floor.
Keep the water clean (regular water changes and gravel cleaning) and add some salt.

You can add rock salt (often sold as aquarium salt) to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres of water.

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, 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, 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.

 

[Colin_T]

Do you feed a lot of blood worms, or color enhancing foods? Rainbows can suffer from nutrition deficiencies that cause bumps that will eventually turn to sores, then pits.

The bumps that turn into a pimple and then a sore, are ulcers that are often associated with fish TB. Lots of plant matter in their diet helps reduce the incidence of the sores and other health issues in rainbowfish.

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If either of you are interested in rainbowfish, you can check the following link. It is written by Adrian Tappin, one of our leading authorities on rainbowfishes. You can click the "Contents" link on the top right to view different species, or there is a pdf link at the bottom of the page if you want to download the book onto your computer. It's a free download.

Rainbowfish Book

A website dedicated to Rainbowfishes of Australia and New Guinea

rainbowfish.angfaqld.org.au

 

[AdoraBelle Dearheart]

The bumps that turn into a pimple and then a sore, are ulcers that are often associated with fish TB. Lots of plant matter in their diet helps reduce the incidence of the sores and other health issues in rainbowfish.

----------------------
If either of you are interested in rainbowfish, you can check the following link. It is written by Adrian Tappin, one of our leading authorities on rainbowfishes. You can click the "Contents" link on the top right to view different species, or there is a pdf link at the bottom of the page if you want to download the book onto your computer. It's a free download.

Rainbowfish Book

A website dedicated to Rainbowfishes of Australia and New Guinea

rainbowfish.angfaqld.org.au

Thanks for this link! I'm interested in having a rainbowfish tank at some point, so that download was a good tip