What is wrong with my Dojo?

[Coolysd]

Can someone please look at these pics and let me know what I need to do?
I have 3 Dojos, 2 of which I've had since Aug 8th and this one I got on Sept 18th. The first two have been growing like normal, however this one has hardly grown at all. I just noticed the darkness around his booty and it was not like that this morning.
What do I do?

 

[Coolysd]

Welp after a Google search it appears that I can use API General Cure. Hopefully that does the trick

 

[Ichthys]

Looks like something it ate ?

 

[Coolysd]

So this morning he seems to be fine. I guess he passed it during the night. I wonder if it has anything to do with the shelled peas I fed them the day before...? Anyway, still concerning that he hasn't grown much.

 

[speakerman3]

It almost looked like it had swallowed and passed a whole sinking pellet. If you feed them sinking pellet food, you might want to ease off for a while or just make sure that what you put in is small enough for your fish to handle or too big for them to swallow whole.

 

[speakerman3]

The gasping at the surface could also indicate too much ammonia or another water parameter problem, but passing something that big relative to body size would make just about any creature gasp for air.

 

[Coolysd]

Over the last few days the only other thing besides the peas have been some bug bites. The pellets and wafers are always put in a grinder prior to feeding.
As for the gasping, ya know they say that Dojos typically don't go to the surface for anything. So not the case with my 3. They will take any food they can at the surface and then drop to the bottom and look for more. They are very entertaining to say the least!

 

[Ichthys]

Dojos typically do take in air at the surface. They’re like Corydoras and Plecs. If there’s not enough oxygen in the water they’ll supplement it with air from the surface.
Also fish in tanks don’t always stick to their ‘natural’ behaviour, especially when it comes to food.