Puffer With Weird Stomach

[attibones]

One of my dwarf puffers, Kahlo, has a really odd tummy shape lately. I've included a picture of both him and his female friend Frida for comparison. His stomach has never been as full as hers, but this is a very abnormal stomach for him.
 
He and Frida share a planted ten gallon, which is heated to about eighty-two degrees, has a sponge filter and a cycled TopFin10.
 
Last water change was about ten minutes ago. Before then, last Sunday or Saturday, about a week ago.
 
They eat frozen bloodworms and about two live snails each every other day. I'm not sure if I'm overfeeding them or not, actually. I've personally never seen them poo, but the poo on the substrate does not appear abnormal.
 
They have no other tank mates. Kahlo's stomach didn't look like this bad yesterday or the day before (though his stomach has never been totally rounded). Today he's been extra shy. He's usually the more timid of the pair. He also refused the live snails I offered, which is extraordinarily unusual. He and Frida have never turned down a snail before. Any ideas?
 
I will post test results in the morning, but it's very late and I've already taken my sleeping pill.
 
(Side note: definitely realized that I should increase the water changes. I didn't realize until today how the detritus builds up in a certain corner) 
 
Kahlo:

 
Frida:

 
The image quality of the last one is very bad, but you can see the outline of her stomach, so I hope you get the idea?

 

[KieranBoyne]

His belly looks like it's been sucked in doesn't it. Weird one that. I think that it could be from either a bacterial infection or even parasites, which I think are always in the water but when there is a decline in water quality there effects become apparent. What are your water test results?

 

[attibones]

Ammonia is 0.
Nitrite is 0. 
Nitrate is 0-5, definitely under 10.
 
I offered a few snails. As per usual, Frida tackled the first one. Kahlo seemed interested though. He's a little pale, but he's showing his yellow on his tail and face. His spots are just sort of washed out. I'm going to defrost some tasty bloodworms and see if he goes for any of those.

 

[KieranBoyne]

Cool. Did he go for them?
I would be prepared to get an anti internal parasite treatment as i think that is what it is. I think you caught it early. Your like a hawk lol.

 

[attibones]

I didn't see him take any. Right now I don't have the money for a parasite treatment, so I'm going to wait and see. I'm doing some research now to see if there are any other diagnoses which may fit.

 

[attibones]

Just did another water change. Kahlo's darkened in color, which is a good sign. He's much closer to his usual coloring. I found some dead snails in the tank which had fuzzed over. Did a substrate vacuum and now all the problem shells are gone. I try to clean out the empty shells every few days, but these were very close to one of their hiding structures so I've missed them. I am hoping that was the problem and that it is now going to get better. I'll do another water change tomorrow to be sure I've gotten everything up.

 

[Alm0stAwesome]

A sunken belly is usually a sign of internal bacteria or parasite infection. Unfortunately I'm not great at disease diagnoses but I would be concerned. 

 

[KieranBoyne]

I understand that you don't have the money. Just keep 2 very close eyes on him, hope he pulls through for you.

 

[attibones]

The only medicines I have on hand are tetracycline. I think I'm getting some money in my account today, so I may be able to pick something up. He's pale again, but he isn't hiding. I'll do another water change soon and see what happens. First I'll offer some snails.

Internal parasites or bacterial... I'm having a hard time finding specific illnesses which would point to his symptoms. 

 

[KieranBoyne]

Ill have a look for you
Well, its definitely internal parasites. It feels weird me answering your questions, its normally the other way around lol.

 

[WILDER]

I agree. Dunken in tummy can be caused by an internal bacteria infection, or internal parasites.
 
What does it look like when he goes to the toilet.
Also check the fish anus to see if its enlarged or red and inflamed.

 

[attibones]

As I've mentioned above, never actually seen him eliminate. I checked his anus. No signs of inflammation or redness or anything. Offered two snails, he killed and ate both of them. His colors are coming back. His stomach looks a little rounder.

 

[WILDER]

Bless Him. He's so cute.
 
I think I would be tempted to isolate him and try an internal bacteria medication.
Hope he's not digesting bits of the shell and getting internal  blockages.
I would also try some daphnia to flush him throw.
You can also add a drop of cod liver oil to the fish  mouth but you can't feed the fish for a few days.

 

[attibones]

I watch him eat the shells and it appears that he spits them out. 
 
If it is an internal parasite, which seems likely, wouldn't it try to attack Frida? She hasn't shown any symptoms, but don't I need to protect her too?
 
I'll try to get some daphnia for him soon. I've also got brine shrimp on hand, but the shrimp don't interest him. Hope that some daphnia or something will help too.

Bless Him. He's so cute.
 
I think I would be tempted to isolate him and try an internal bacteria medication.
Hope he's not digesting bits of the shell and getting internal  blockages.
I would also try some daphnia to flush him throw.
You can also add a drop of cod liver oil to the fish  mouth but you can't feed the fish for a few days.

 
Oh, wait, you said bacteria. I've still got tetracycline. I'll throw that in there. If it's bacterial, I would rather treat the whole tank to prevent Kahlo from being infected upon coming back into the main tank.

 

[WILDER]

The tetracycline will wipe the good bacteria out in your filter. As long as you know that's fine.
 
These are the signs of internal parasites.
Long stringy white waste. Or clear waste.
Enlarged anus, red inflamed anusl.
Fish will look skinny, or bloated, sunken in belly region.
Worms sometimes sticking out of the anus.
Fish will sometimes swim on it's side.
Spitting food out.
Sometimes bent spine.
Flicking and rubbing.
Secondary bacterial infections.