My Id Shark Is Dying What Do I Do?

[fishlover500]

My iridescent shark is dying he is about 2 inches and in a 30 gallon (i know he grows huge but I love to house these guys even for a small while) I have 2 of the same size that i have kept for about 6 months in there and have since become really
attached to both of them, they both eat well and have full stomachs.

This guy was lying on the gravel and still breathing, I don't believe he was gasping for air, he would occassionally try to swim
but he got about up and inch and sord of uncontrollabley crashed back. As i have said normally his stomach is very full but at the moment his belly is CRAZY sunken in what do I do!!!!?!?!?!?!?!!?!

 

[WILDER]

Can you post your water stats in ammonia, nitrite, nitrate, and ph.
A sunken in belly can be internal parasites sign are.
Long stringy white poo, clear mucas poo.
Worms prutruding form the anus of the fish.
Enlarged anus, or red inflamed anus.
Being skinny or bloated.
Bent spine sometimes.
Sunken in belly.
If a fish is infested with internal parasites they do alot of damage to the organs and brain.

 

[fishlover500]

Sorry can't give water stats but the tank has in it

4 platys
1 cherry barb
4 zebra danios
1 giant danio
2 bala sharks
1 bushy nose plecco
2 id sharks

other ID shark is perfectly healthy and this guy was to till about 2 days ago where he Suddenly came down with this
Are internal parasites contagious??

Tank has always had reasonable water changes and has had one in the last 2 weeks (I think) it also has a monster
filter (emperor biowheel 400)

 

[WILDER]

Your tanks severely overstocked for a 30 gallon.
Plus lfs shouldn't be selling ID sharks as they grow to big for tanks, sadly most of them never make it out of the infant stage.
I would take a sample of your water to the lfs and tell them to write the readings down for you.
Also I would suggest a water change, and invest in some liquid test kits in ammonia, nitrite, nitrate, and ph.
I would take the sharks back to the lfs if you can't updgrade now.
The shark that has a sunken in belly has he been eating and not lost weight due to not eating.
The whole tank will need treating if the shark has internal parasites.
Sometimes the med to late for the fish that has the internal parasites as it does alot of damage to the internal organs and brain.