Rainbow fish with lock jaw ???

[Doozie]

Since last night, one of my rainbow fish now has his mouth permanently open, it seems like his jaw is locked or something. Does anyone have any advice what to do or why this is happening?

My tank is 4 ft long (48x18x15) and runs on an external filter.
5 x rainbow fish
4 x albino corys
1 x ruby shark
1 x angel
1 x bn plec
1 x dwarf gourami
2 x rams

what should I do to help him?

 

[Doozie]

anyone??????????

 

[craig_uk]

Tank params would be a start i'm afraid, and without pics its pretty difficult too.

Is he still able to eat?

craggy

 

[Doozie]

The tank is 46 gals. I measured the water and all the readings are good - ammonia, nitrate, nitrite 0, pH 7.

No pics I afraid (camera bust) but basically imagine a fish with his mouth permanently open and that's what we're dealing with. His bottom lip looks a bit swollen. The fish still swims normally although struggles at feeding time!

I wonder if he's been scrapping with the other rainbows and broke his jaw - is that feasable?

 

[nfored]

Is this tank heavly planted? if not and your nitrAte is 0 then you test kit may be bad, also how long has this tank been setup? very unusal to see all zeros unless its not cycled yet or is very heavly planted.

 

[Doozie]

The tank is 5 months old, and certain fish (like the shark) have been in it since the first month and look healthier than ever.

You have got me worried though, and maybe I'll take a sample of water to the LFS to confirm my readings. There are no live plants, only plastic ones.

Any ideas on the open mouth?

 

[Lizardking]

what kind of rainbow is it?

 

[Doozie]

bosemani rainbow fish, about 2 inches long.

 

[Lizardking]

Is it the alpha fish whos got the damage? It could have occured from a fight over pecking order.

 

[Doozie]

Not sure who's the alpha yet, as I only bought the rainbows last weekend.
On first reflections though I would guess that he isn't - maybe he got his ass kicked?