Harlequin Dying, Haemorraghing Internally

[daizeUK]

One of my six harlequins is looking extremely sick.  He is swimming slowly and gasping/gulping, although not at the surface.  Occasionally he drifts down into a plant and goes belly-up and rests there for a short while, then rights himself and moves off again.  He seems to be getting weaker and looks like he has some interal bleeding in his midsection.
 
I've had the harlequins for 2 weeks and water stats are perfect.
 
I doubt there is anything I can do for this one, it looks like he's on his way out   I am worried in case this is a disease that could affect the others.  
 
Advice appreciated.

 

[daizeUK]

'Emergency' is now over - I took the decision to euthanase the poor guy.
 
I'd hoped I'd never have to use that bottle of clove oil I bought.  I hope I helped him pass more easily.
 
If anyone can explain what was wrong with him and whether I may need to treat as a disease I'd appreciate it.

 

[Ninjouzata]

Sorry for your loss! 

Unfortunately I have no idea what that could of been.

 

[daizeUK]

Thanks, Ninjou.  I've just inspected and there appears to be a shallow external injury so I'm guessing it's not disease.  I have no idea what could have caused it because there are no aggressive fish in the tank.

 

[KirkyArcher]

Sorry to hear of your loss Daize, Is it at all possible that he could have been partially sucked into the intake strainer of your filter, and eventually made an escape causing the injury that's a side effect of having higher flow rates (high intake suction) I eventually hollowed out a internal filter sponge and covered the intake, other folk use netting. (this coincidently is how I had my 1st fatality in my 125l when I switched from internal to external

 

[daizeUK]

I don't think so, the inlet strainer is well protected and none of the fish are small enough to get sucked in.  I have threadfins in the same tank who are coping quite well with the strong flow and the harlequins are much stronger swimmers than they are.
 
All I can think is he might have scraped himself on a rough piece of hardscape but it's strange because the harlequins mostly stick to open water in the upper half of the tank.   I guess I'll have to put it down to an unfortunate accident.  Cheers Kirky.