Guppy fins bubbling?

[Darcytulullah]

Hi everyone, i hope you can help me!

My white guppy from my 54L tank has developed strange bubbles on his tail and fins (pictures attached), i have never seen anything like it. The fish is still alert, eating normally and doesn't seem to show any signs of discomfort or trouble swimming.
Nitrate in the tank has been a problem for a few months but i've recently added nitra-zorb to the filter which seems to be improving it but as of the last reading on 30/05/20 the nitrate is 40ppm. Ammonia and nitrite are 0ppm and PH is 7.8.
Filtration is a fluvel U1.
The tank is currently stocked with 7 cardinal tetras, 9 male guppies an 5 false julli corys.
I do a 20L water change once a week and vaccume the gravel to remove any waste i can see when i do this.
This is one of the original fish i had in this tank which i first stocked last october, i noticed that it's fins looked a bit different to the other guppies in the tank but had always assumed this was down to bad breeding or the fact he is pure white maybe giving him a different fin shape to the standard colourful guppies.
I recently changed my filter to the fluval U1, before that i was using the jewel filter that came with the tank but when this broke i replaced it with the fluval filter on the same day and transferred the old filter media into the new filter to preserve the bacteria.
I feed my guppies and cardinals NT labs probiotic tropical food, and the corys the catfish variety of this food, i've never changed their diet.

Has anyone seen anything like this before? I currently have him in a hospital tank treating with melafix and pimafix as i have no idea what could be causing this or whether it could be contagous to the other fish, any advice would be greatly appreciated.

 

[Dallascowboys16]

I have never seen something like that before. It doesn't even really look like a disease, more of a deformation of the fins. I wish I had more information for you, but this is very strange. The closest thing I have hear of is GBD or gas bubble disease. It is more common in fancy goldfish so maybe a forum specializing in them may have more answers.

 

[Darcytulullah]

Thank you for your quick reply!

As I said he seems to be healthy other than the strange fins so perhaps it is just a deformity that he’s adapted to living with, he doesn’t seem to be in discomfort or struggling to swim at all and is still eating and alert just like all the other guppies. He’s even gone as far as to be nipping his rank mate in the hospital tank (I’ve separated them now that I’ve noticed him nipping).
As for GBD I can’t see why he would have this, none of the other fish in the tank show any symptoms like this at all so I think a deformity sounds like the most reasonable explanation. If this is the case I’ll stop treating him and put him back with the other fish

 

[fishingBuds]

The most common causes of*fin*rot/deformation are poor water quality and improperly-low water temperature. Overcrowding the*tank, feeding outdated food, overfeeding the*fish, and moving or handling can also cause stress that leads to*fin*rot or deformation