Gem tang 0 : ?? 1

[ffiren]

I noticed a sizeable chunk out of the dorsal fin on my beloved gem tang.

Peacefully cohabited for > 6 months with 2 x mocha clowns, 1 x naso tang, 1x 6-line wrasse and a pair of mandarin... I've never observed any aggressive behaviour, particularly from the naso, though he is clearly top of the food chain.

Does the naso go into time out, or watch and wait?

 

[P-Dub]

If you do not see any overt aggression from the other fish, I am leaning towards fin rot, based on the photo and the visible damage to the fins... Maybe QT/hospital tank time for the Gem.
@Jay Hemdal

 

[ffiren]

I currently have a QT setup with copper...Don't have any medication and don't want to needlessly stress him out.

crap. advice?

 

[P-Dub]

I currently have a QT setup with copper...Don't have any medication and don't want to needlessly stress him out.

crap. advice?

Patiently wait for @Jay Hemdal. He is the sick fish guru.

 

[ffiren]

Patiently wait for @Jay Hemdal. He is the sick fish guru.

Patience is a virtue in this hobby and the plot thickens...

The other fish are fine and I did have a gem previously that this happened to. Exactly the same marks on the fins. I also thought it was fin rot.I QT and medicated with metronidazole, which was recommended by my LFS. We have to import this and there was a 14day shipping time from the states, but being a doctor I wrote my fish a prescription for metronidazole in suspension. The stuff you give to kids. Reconstituted with RODI. Was very careful with the maths but it did not end well. 24hrs later the gem was dead. Convinced it would have been better if I left it alone, hence I'm hesitant to act on impulse this time.

 

[Jay Hemdal]

Patience is a virtue in this hobby and the plot thickens...

The other fish are fine and I did have a gem previously that this happened to. Exactly the same marks on the fins. I also thought it was fin rot.I QT and medicated with metronidazole, which was recommended by my LFS. We have to import this and there was a 14day shipping time from the states, but being a doctor I wrote my fish a prescription for metronidazole in suspension. The stuff you give to kids. Reconstituted with RODI. Was very careful with the maths but it did not end well. 24hrs later the gem was dead. Convinced it would have been better if I left it alone, hence I'm hesitant to act on impulse this time.

This does look like mechanical damage to me. The location leans towards a bite by another fish. These sorts of injuries usually heal on there own as long as the damage doesn’t keep happening. Secondary bacterial infection can happen though.
It is unlikely to be a primary bacterial infection, but not impossible. Evidence of that would be a rapidly growing size of the lesion.
Metronidazole is primarily anti parasitic. It has some effect on anaerobic bacteria, but on the outside of the fish, bathed in oxygenated water, any bacteria present should be aerobic. Most fish pathogens are gram negative.
Jay

 

[Jay Hemdal]

I noticed a sizeable chunk out of the dorsal fin on my beloved gem tang.

Peacefully cohabited for > 6 months with 2 x mocha clowns, 1 x naso tang, 1x 6-line wrasse and a pair of mandarin... I've never observed any aggressive behaviour, particularly from the naso, though he is clearly top of the food chain.

Does the naso go into time out, or watch and wait?

Looking at the picture some more - is there minor erosion on the edge of the fin before the damaged area? If so, that might lead me more to this being primary bacterial fin rot and not from aggression.
Jay

 

[davidcalgary29]

Time to break out the spy cam! Stealth is sometimes required to ferret out sneaky aggressors.

 

[BiggestE22]

I noticed a sizeable chunk out of the dorsal fin on my beloved gem tang.

Peacefully cohabited for > 6 months with 2 x mocha clowns, 1 x naso tang, 1x 6-line wrasse and a pair of mandarin... I've never observed any aggressive behaviour, particularly from the naso, though he is clearly top of the food chain.

Does the naso go into time out, or watch and wait?

I would. E pretty ticked. Gem Tangs are top 3 of reef safe most beautiful fish

 

[ffiren]

Past 11pm here so lights are off. Will try and get a better pic tomorrow. Feeding well

 

[ffiren]

Sorry for the delay - hectic work schedule.

I spent ages trying to get better pictures. The gem will take food from my hand but as soon as a camera gets near it, it's gone....

In any case, made a concerted effort to really 'feed the tank' with enriched premium foods and the fins healing. There's only the slightest mark visible now. Maybe was the naso in the end. Anyway, it's healthy but has gained in girth!

Glad i didn't overreact this time. I'll try and get a better picture at some point.

Thanks for your help guys

 

[ZoWhat]

Dont think a tank size in horizontal feet and gallon capacity was talk about. I'd be interested to know that as Naso can get huge with streamers

I think aggression will just get worse as Naso grows

 

[Jeffcb]

My Gem Tang has busted several rays on its fin as well. I have seen several other Gem tangs with broken rays.

My Gem tore its fin between 2 rays and it healed back with in a few days. Once the ray is broken I don't know if or how long it takes to grown back.

 

[ffiren]

The naso is actually really placid. You just don't get between him and food.

 

[P-Dub]

I spent ages trying to get better pictures. The gem will take food from my hand but as soon as a camera gets near it, it's gone....

Clearly, you did not get a signed model release from the gem...