Danio acting very strange

[batman669]

I have a leopard long-finned danio that seems to be hiding under a rock and sitting in the gravel. It is the first I have ever seen it do this. I have noticed it has gotten pretty fat in the past couple weeks. It also seems to 'panic' when anyone approaches the tank.
I've just gone through a sickness in the tank, I don't know if this is related or not. Another danio just passed away, it seemed to be deathly skinny. Old age?(like 3-4 years old)
I am really lost. Still don't know what sickness I had and if its completely gone yet.

Please Help!!

Tank parameters are pretty normal.
Ammonia low
I've added aq. salt to help relieve stress, but still at a loss.

!!!!!!
_batman

 

[The-Wolf]

it sounds like swim bladder parasites
check this link out for agood diagnosise site

as for the "pretty fat" she may have eggs

 

[cat.fish]

Fish has swollen abdomen (dropsy). Possibly raised scales and some reddening on the body or fins. They may possibly exhibit pop-eye (exophthalmos)

1) Viral infection.

2) Systemic bacterial infection. leading to 'dropsy' (build up of fluid in the abdomen. Can be differentiated from tumour by shape, symmetry and feel (feels soft and fluidy)

3) Neoplasm (tumour). Can usually be determined by size, shape (usually asymmetric) and palpation (feeling - usually hard)

4) Heart or kidney disease. Can only be diagnosed by post mortem

5) Internal parasites (endoparasites)

6) Genetic disorder

7) Intestinal blockage. Only established at post mortem


THOSE ARE NOT MY WORDS

I found that on the site that danio gave