Hi everyone. I'm new poster and was looking for some advice. I'm fairly new to the freshwater tropical tank game and have had a couple of mollies for a while now. One of them, shown in the attached images is looking really large at the moment but I can't tell if they are pregnant or just in need of a diet! Any advice would be appreciated.
Many thanks
Hi and welcome.
Before we get into the issue directly, I need to ask: has the tank gone through the cycle yet? How often do you do a water change and how much do you change when you do change water? Have you tested the water parameters recently? Are you sure this is a female fish? You can tell by the shape of the anal fin ( the fin nearest to the fish's anus. )
The fish on top is a female, the bottom is a male. The male's anal fin rolls up into a tube which is his reproductive organ.
As for your question:
This appears to be a balloon molly or have balloon molly genetics in it so this is going to be a tough one to answer positively because there are 3 possibilities. For starters, fish rarely need to go on a diet so you can rule that out. ( Usually to get a fish so fat that it needs to go on a diet means you are heavily overfeeding the tank and the water would be very polluted.
)
If the other molly in the tank is a male or your fish was in a tank with males, your fish is most likely pregnant. Mollies have the ability to hold sperm for a later pregnancy so the fish just needs to be in the presence of a male for a short time and not in constant contact. Your tank appears to be planted so if you have a lot of frilly style plants in there, that will be a good area for the mother to give birth in and the fry to hide in.
Unfortunately, because the fish and substrate are similar in color, it's hard to tell from your picture if your fish has a condition known as dropsy. Dropsy is a condition where the organs of the fish stop functioning and is usually caused by an internal infection. When the organs stop working the fish losses the ability to regulate the fluid within the body so they swell up. In the advanced stage of dropsy, the scales will start to protrude to the point where the fish looks like a pinecone. At this stage, the condition is usually fatal while the only real time the condition is reversible is early on. This takes antibiotics which, since I see you are in the UK, they may not be readily available to you.
The third possibility is constipation. Do you see the fish continue to feed and have eliminations? If yes, constipation is most likely ruled out as the cause. If not, we would need to delve deeper into this.
Hope this helps.
