Fast Deforming Disease In Rainbow Fish

I have been away for 48 hours and come back to a very sick fish. I lost a bloated fish with what looked like dark red flukes (maybe) from the Lower gills. I treated the tank for flukes and water parameters are normal (no ammonia or nitrites and trace nitrites) the other fish are well. I have 18 dwarf neon rainbows, 3 Keyhole Cichlids, 40 green neons, 7 cories, 9 otos and 3 rubbernose pleco. In a 328litre planted tank.
I have no idea what would cause this rapid decline, twisted spine, discolouration and erratic swimming? This is something I have never seen before. His mouth is also totally open and it looks very dark red inside. He’s very skinny also, but totally well looking on Friday afternoon. Any advice very welcome.

 

I'm pretty sure the affected fish is suffering from an intestinal bacterial infection. Columnaris can cause spinal bending as highlighted in your pic.
Its best to remove any fish exibiting symptoms asap. You can try to medicate with antibiotics but recovery is unlikely.
Be a good idea to drop the temp a couple of degrees and do a large WC. Just keep the tank clean, watch the tank mates for symptoms, things will likely get back to normal soon.

 

Thank you! Can I treat the whole tank as a preventative do you think?

 

I wouldn't. The bacteria likely took hold of a weakened fish. The healthy tank mates immune systems were able brush it off. If an infected fish with Columnaris is allowed to stay jn the tank, its body will act like an incubator, enabling the bacteria to become more virulent.

 

Thank you I bought a Green Killing Machine UV Steriliser, would that help protect the others do you think? Sorry for all the questions, but it has totally taken me by surprise! I do 50% water changes every week and I am quite attentive and particular about my water quality, didn’t expect to see such a horrible sight when I got home today

 

Bacterial infections can occur in pristine water conditions, but are more common in bad. UV Sterilizers are pretty good at killing parasites, but I'm not sure about bacteria.

 

Thank you so much. I will do my best to look for early symptoms and get them separated. I have a hospital tank running.

 

YouI did remove the effected rainbow right ?

 

I did, straight away. All the others look good apart from one who has very VERY slightly lost the sheen on her side. Shall I remove her just in case? In fact I can’t see it but my daughter assured me she can!

 

Keep an eye on that one especially close .

 

Bacterial infections can occur in pristine water conditions, but are more common in bad. UV Sterilizers are pretty good at killing parasites, but I'm not sure about bacteria.

Yes UV light kills many of the bacteria that can infect fish. I'd recommend getting that in the tank ASAP.