Bloated Leopard Danio Fish

Question
I recently got a fish bowl with 2 Leopard Danio Fish. I've had them both for a week and one of them has really bloated just underneath the gills. I have a friend who thinks it could be pregnant...but i didn't really think fish could be pregnant like that and then i have another friend who reckons it could be an air bubble and that my fish is going to die soon. I would love to have some professional advice about what it could be and whether i could do something about it!! thanks !!

Answer
Hello,

First of all, let me apologize for my [extremely] delayed response.  This AllExperts thing lets you take "vacations" every now and then, but it doesn't tell you how to do it.  So now I'm answering 21 questions tonight.  We'll start with you. :)

I'm going to assume by "fish bowl" you mean just a simple little bowl with nothing but fish and water and maybe some rocks and decorations.  Danios are not fish that can survive for long without a filter and aeration, so if your tank has this, great; if not, I would advise getting a small aqarium for them instead of just a bowl.

When a fish looks bloated around the gills or just below, it's usually either constipation, bloat, or another internal bacterial disease.  Danios are egglayers, so it's not very possible that your fish is pregnant.  They will swell up with eggs when they're ready to spawn, but it's very unlikely that this is the case.

So if your fish are in a filtered, aerated aquarium, then there's really nothing you can do for him, he'll just have to work it out himself.  Chances are it's a bacterial thing and he will die from it.  If they are in just a bowl, get a filter and air pump in there as soon as you can, or move them to a small aquarium, because they really will not survive without oxygen being pumped into the water.

I hope this has helped, please feel free to respond if there's more information or anything else you'd like help with.

-Lindsay