Poorly Green Chromis

[TinaH]

This little guy used to be one of 3 Green Chromis in the tank, but over the last year his 2 friends died off. We noticed our last little Chromis was getting bullied. He had a few nips in his fins, marks on his side and he was hanging around the top corner of the tank out of the way. We have a damsel that can be a bit of a bully, but not normally this bad. We popped a breeding box in the tank the in the Chromis safe corner so the he had somewhere to escape to. It's been a month or so, and he was improving, he's barely using his safety box now, he's swimming around, eating normally and his fins had grown back and marks had healed up into little dots but he is still looking poorly. I checked in on him today as he was really close to the front glass facing the other way to usual and I noticed this big round bump on his side. Does anyone have any idea what this could be? All other fish in the tank are healthy, the bullying has died down. We feed twice a day and he is eating. I've googled possible diseases/parasites and nothing seems to match!?

20260528 111420(1) hosted at ImgBB

Image 20260528 111420(1) hosted on ImgBB

ibb.co

 

[vetteguy53081]

This little guy used to be one of 3 Green Chromis in the tank, but over the last year his 2 friends died off. We noticed our last little Chromis was getting bullied. He had a few nips in his fins, marks on his side and he was hanging around the top corner of the tank out of the way. We have a damsel that can be a bit of a bully, but not normally this bad. We popped a breeding box in the tank the in the Chromis safe corner so the he had somewhere to escape to. It's been a month or so, and he was improving, he's barely using his safety box now, he's swimming around, eating normally and his fins had grown back and marks had healed up into little dots but he is still looking poorly. I checked in on him today as he was really close to the front glass facing the other way to usual and I noticed this big round bump on his side. Does anyone have any idea what this could be? All other fish in the tank are healthy, the bullying has died down. We feed twice a day and he is eating. I've googled possible diseases/parasites and nothing seems to match!?

20260528 111420(1) hosted at ImgBB

Image 20260528 111420(1) hosted on ImgBB

ibb.co

These look to be bite marks and likely from another chromis or damsel. It needs to be isolated for best chance of healing in an acclimation box or another tank

 

[MnFish1]

I think isolating certain types of fish just is difficult. A damsel is going to establish territory, and normally they do not just become 'friends' with other fish because that other fish has been in an acclimation box. I would - as suggested above, remove it from the tank. It could be Uronema - as this can live in tanks with or without fish, and is somewhat common in green Chromis, however, there is usually more redness then just injury as noted in your fish.

 

[Jay Hemdal]

This little guy used to be one of 3 Green Chromis in the tank, but over the last year his 2 friends died off. We noticed our last little Chromis was getting bullied. He had a few nips in his fins, marks on his side and he was hanging around the top corner of the tank out of the way. We have a damsel that can be a bit of a bully, but not normally this bad. We popped a breeding box in the tank the in the Chromis safe corner so the he had somewhere to escape to. It's been a month or so, and he was improving, he's barely using his safety box now, he's swimming around, eating normally and his fins had grown back and marks had healed up into little dots but he is still looking poorly. I checked in on him today as he was really close to the front glass facing the other way to usual and I noticed this big round bump on his side. Does anyone have any idea what this could be? All other fish in the tank are healthy, the bullying has died down. We feed twice a day and he is eating. I've googled possible diseases/parasites and nothing seems to match!?

20260528 111420(1) hosted at ImgBB

Image 20260528 111420(1) hosted on ImgBB

ibb.co

Welcome to Reef2Reef!

You called this a bump, but it looks flat to me. It likely started with a bite though, but to me, it looks like it is now a secondary bacterial infection. It might get better on its own if you isolate the fish, but that is best done by moving the aggressive fish out and giving this one more room.
If the spot grows larger though, you’d need to treat it in a hospital tank with a broad spectrum, gram negative antibiotic like kanamycin.

 

[TinaH]

Thanks all for your help. We haven't seen him getting bitten up in a while, but it could be happening after lights out. We have a Humbug Damsel and a Blue Devil Damsel, both are little bullies! The rest of the tank put them in their place but this little guy must be getting the brunt of it. He is the smallest fish we have apart from a little male clown (but he's protected very well by his wife). It's difficult to get perspective with the way hes swimming, but it is a bit of a raised bump that he's got. We have popped him back in the breeding box for now and will sort out a hospital tank for a little while so we can give him some antibiotics, just in case. Fortunately, we have a new tank cyclicing at the moment which will be perfect for him and some more friendly tank mates! Thanks again!