Well I did say this was the last time....

[BlaiseinLondon]

When I got Jonah the plakat koi from my LFS last November I said that it was the last time I was going to try to keep a betta. (Several previous attempts, some years ago, had ended prematurely with fin rot, despite my 'doing everything right'.)

Well yesterday I came back from a long weekend away to find that Jonah has some splits in his top fin. I had Esha 2000 to hand...... but the tank also had four assassins..... Essentially, I had to break down the tank to find the snails and move them to my other tank. (AI tells me that they carry such a small bacterial load that they are unlikely to infect my 90 litre, but I've purchased some snail-safe fin rot treatment just in case.)

I know what's caused this - the ammonia spike about which I posted just before going away, which was (most likely) the result of my three kuhli loaches having quadrupled (entirely unseen - they were always hidden) in size. They, too, are now in the other tank and seem much happier and more prepared to be visible. Perhaps the betta was bullying them when I was not around to see.

So, please cross everything for Jonah!

 

[Naughts]

I’m surprised that fish growing was enough to cause an ammonia spike. What is your water change schedule and how are you cleaning the filter?

 

[BlaiseinLondon]

I’m surprised that fish growing was enough to cause an ammonia spike. What is your water change schedule and how are you cleaning the filter?

Weekly change of 33% and I use an internal sponge filter to back up the in-built one (it's got one of those tray-type filters along the back wall). Clean the filters every couple of months in used tank water. The tank is 30 litres and the loaches were teeny-tiny when I got them, and are now huge!

 

[Naughts]

Well that’s all good, so I agree that the Khulis should be moved as 30 litres was struggling to house 5 fish. I just wonder if you’ve needed to use any treatment that could have killed the beneficial bacteria?
The fins will recover better in really clean water, could you do 50-75% w/c at least once or twice a week?

 

[BlaiseinLondon]

Yes to upping the water changes, no to prior medication

 

[Back in the fold]

I’m always interested in things like this because they shouldn’t happen . I agree with @Naughts that a bit more and frequent water change will help . Clean water is the best medicine . I’m skeptical that the Kuhlii Loaches could be any more of a bio-load because , in my experience , they are light eaters . Some fish crap like big dogs but not Kuhlii’s . I’ll be interested to see how this turns out for you .

 

[Innesfan]

Splits in the dorsal fin, if that's what they indeed are, don't say ammonia spike or water issues to me. Splits are usually the result of excessive flaring or injury. Anything in the tank he could be catching his dorsal on?

 

[JuiceBox52]

I agree with @Innesfan do you by chance have a photo of the fin? Fin rot typically comes along with a visible white or grey outline, sometimes a little bit fluffy of a gray coating, right on the edges of the fins where they are starting to shorten/fall off

A single split sounds more like an injury — but treating with larger and more frequent water changes may help prevent the injury from becoming an infection

 

[GaryE]

To me, splits are a perfectly natural result of perfectly unnatural fin growth. The fins have been modified through linebreeding, and a tendency for them to split is a result. @JuiceBox52 has described fin rot well, but a lot of hobbyists medicate for a natural process based on breeding choices rather than any disease. They flare to show off, and they're like a teenage boy doing karate moves in too tight pants.

 

[BlaiseinLondon]

Splits in the dorsal fin, if that's what they indeed are, don't say ammonia spike or water issues to me. Splits are usually the result of excessive flaring or injury. Anything in the tank he could be catching his dorsal on?

Absolutely not, but thank you. I always check any ornaments. It's a small tank so he has only a piece of wood (all smooth), a floating log (likewise) and some moss balls. The heater has a cover and the sponge filter doesn't have any rough edges.

 

[BlaiseinLondon]

Interestingly he rarely flares (and I don't try to induce it - feel a bit uncomfortable about doing that!).