Betta suspected to have fin rot or columnaris

[Lunamyst]

Hi everyone,

I'm still reeling from the loss of my crowntail Betta, Tassel, who sadly passed away this morning. He was in a 10L betta tank for about 8 months, but the filter started malfunctioning, which led to poor water quality over the last few weeks.

I upgraded to a 28L aqua one ecostyle last week, adding bionoodles from a well-established tank, hoping it would help him recover. However, after transferring him to the new tank with better lighting, I noticed he was unwell - there was a clear, fluffy growth on one part of his tail, and some of his tassels had a reddish tint.

I suspected fin rot and possibly columnaris, so I medicated with TriSulfa tabs, but unfortunately, it was too late. I've attached a photo, though you can't see it, he also had the same fluffy growth on his head, not just his tail.

I'd really appreciate it if someone could confirm my suspicions. I'm also seeking advice on how to proceed with the new tank. I've read that I should wash the tank, sand, and decorations with boiling water, and replace the filter media, seeding it with biological media from another tank. I also have hydrogen peroxide, which I've heard can be used to disinfect the tank.

Any guidance on how to properly disinfect and prepare the tank for new fish would be greatly appreciated.

[coltin]

I think it's likely your Betta suffered from ammonia or nitrite poisoning, which would've damaged his internal organs and fins, and then a bacterial infection took over. The colouration on your Betta was quite unique, which makes it even more disappointing.

Considering he was the only fish in the tank for 8 months with no new additions, I highly doubt it was Columnaris.

As for your new tank, just give it a good rinse with water, set it back up, and wait about a week before adding a new fish. If you're still concerned about diseases, you could try adding a lot of salt to the tank so it's fully saturated, let it run for 24 hours, then rinse it out and let it dry for a couple of days. After that, set it back up, wait a few more days, and you're good to add a new fish.

In the future, if you notice your fish getting sick or unhappy, or if the filter starts malfunctioning, just reduce feeding to once every three days and do a 75% water change daily until things get back to normal. Poor water quality is usually the culprit behind fish deaths, and it's often caused by overfeeding and inadequate filtration. Don't worry about your fish starving, though – they use food for movement and growth, not to stay warm. They can actually go weeks or months without food, but if you overfeed, you'll get an ammonia spike and your fish will be gone in no time.

[goldminer]

I've heard that phrase before - 'a slightly hungry tank is a healthy tank' - and it really does hold true, especially for those predatory fish in the wild. They don't eat every day, unlike our aquarium fish that are fed daily. For inactive fish like Bettas living in smaller tanks, 5 gallons or less, they really don't need a lot of food. Two or three small pellets a day is more than enough, trust me. My condolences on your loss, Lunamyst.

[Lunamyst]

I really appreciate the advice, Colin and goldminer. Colin, I think you're right - it was probably a combination of poor water quality and a bacterial infection that got him. I'm considering the salt treatment as a precautionary measure. Your tips on managing water quality and feeding are really helpful, and I'll definitely keep them in mind for the future.

goldminer, I don't think I overfed Tassel, but I can see how I could have been more careful with his feeding. Your point about a slightly hungry tank being a healthy one is well taken. I'll keep that in mind going forward.

I'd like to share a photo of Tassel in his healthier days, to celebrate the good times we had with him.