Zebra Danio

[xXBatmanxX]

I currently have 4 Zebra Danios. There is one specifically at this moment that keeps getting fatter and it always at the bottom. I have noticed that it keeps getting bigger every week only at its belly area. I need help on what could be happening. I think the fish might be pregnant but I need help on what it actually could be. 

 

[hudsona85]

Could be many things. A picture would help assisting you on what it could be.