My largest Danio, a Long-Finned Leopard, has recently become quite plump. I know more about livebearers than Danios, so I need some help. First, I don't know if he is a she, or if she's a he, or what it is. I do know it is a very attractive fish. Well, I came home from work today to find that she had become rather fat. I don't know if it is just that, fat, or if she is pregnant and ready to lay some eggs. She is living in a ten gallon tank with other Danios and some Platies. Below you will find a picture of the little guy. What do you all think?

Did she become fat all of a sudden? The fish looks like an egg laden female to me although a little big. I've had a lot of danios with tuberculosis which makes danios really fat. Normally, in that case, the "fatness" is bumpy and not even. Hers seems pretty even. I'm not 100% sure though; it could be an internal bacterial infection like tuberculosis. That usually doesn't spring up overnight though so if she got fat quick, it's probably eggs. If there is no male around, she will either reabsorb the eggs or develop an infection from them which is more rare and would appear as her being and staying fat and later acting ill. I hope it's just normal! The larger danios in a group are almost always female.

It may not have been "overnight" sudden, but it was pretty quick. It had been a while since I took a close look at her. I had been focusing a lot on my two baby Platies instead. Also, her contour is pretty even. There are other Danios in the tank. There are six or seven, a combination of Leopards and Zebras. All the others look normal, with no excess weight.