Clown fish tail fin missing mystery

[Leaellynasaura]

I recently purchased a gold stripe maroon clown fish. It made it through 4 weeks of quarantine with no problems. I put it in the display tank and soon after there was an accidental rock collapse that was major and violent. After dealing with that and miraculously having no coral damage a few days later I noticed the clown looked a little roughed up and was missing a large part of his tail fin (not the meaty part.) I suspected the rocks must have fallen on him somehow. A week later I noticed more of the fin was gone so now I am doubting the rock collapse causing the fin loss. There is no presence of fuzz or disease that I can see and his behavior is normal and his appetite healthy.

Tank mates include a few small hermit crabs, 3 mollies and 1 Banggai cardinalfish. The clown like to swim among the tentacles of a large tentacle plate coral. Is it possible that while sleeping the plate coral is taking bites out of his tail?

 

[DLHDesign]

Unlikely that the plate coral is doing the damage, IMO. I'd suspect that the Cardinal is the culprit; I had one that was a bit on the aggressive side, which is not uncommon for them.

Do you have hospital/QT that you could set up? If so, I'd suggest moving the clown into that to give it some time to rest and recover. Might want to ensure you have bacterial medications ready just in case, though these may not be required at this point. If you can get a photo of the fish, that would help.

 

[Leaellynasaura]

Hard to get him to sit still for a photo!

 

[Frtdrmrose7]

he Looks like he has been picked on quite a bit, I would get him into QT and treat with ABX’s for a bacterial infection. I would give him a bath in Ruby Reef Rally then into QT with the Trifecta. (Metro, Kanaplex, Furan 2). I would also be looking for the aggressive fish and getting ready to separate them.

 

[Mastiffsrule]

+1
How big is the tank. The cardinal may be protecting his territory at night when it is time for bed.

I hope they learn to get along.

 

[Leaellynasaura]

The tank is 135 gallons. I have never seen the cardinal fish make an aggressive move and when its feeding time the clown and the cardinal are often in close proximity with no interaction.

 

[Leaellynasaura]

Wow, such bad luck I have had, another huge rock collapse today. Took forever to fix it and now then clown is balls deep in that plate coral again as the lights go down. I think he will be fine.

 

[ngoodermuth]

Some of those marks on his head and body actually look like hypermelanization, happens when clowns try to be hosted by stinging corals in place of an anemone - in this case your plate coral obviously.

The white margin on the wound on the tail is a bit concerning, could be a secondary infection... I agree that QT to rest and recover with antibiotics at the ready would not be a bad idea. Otherwise, watch very closely- if the white discoloration gets worse or the tail looks like it is deteriorating - you'll have to move quickly. Unfortunately, sometimes by the time it appears serious enough to "react" it could be too late.