My Molly fish has a swollen belly and is isolated. Pregnant or ill?

The natural antibiotic properties of Melafix work best with minor or external infections. Your Molly may be quite ill and may need more aggressive treatment. If you have other fish in the tank, especially Bettas or Gouramis, you cannot use Melafix as this could harm them. Separate the molly to a hospital tank and treat there. You will need to remove the carbon filter insert during treatment or it will filter out the Melafix. The symptoms listed may indicate bacterial infection, parasites, constipation or obstruction. If Negrito has a pinecone appearance, he may have a serious infection (dropsy) that is causing kidney failure. This would in turn cause the swollen abdomen and lack of appetite. Check the water chemistry, temperature and filtration. Ammonia and nitrites should be absent and nitrates can be present at 40ppm (parts per million) or less. Molies do best in water between 75F and 80F. Perform a partial water change if necessary to stabilize chemistry and maintain water quality. Use only aged or conditioned water that is temperature matched to prevent further stress or shock. Clean water is the best way to manage any infection. Plain aquarium salt (NOT table salt) can be used at 1 teaspoon per gallon of water but it is not recommended if your molly has dropsy. In this case, Epsom salt can be used to decrease swelling. Allow a 15-30 minute swim in a bath prepared with 1 tablespoon of Epsom salt per gallon of water. Do this in a separate container. It could help with constipation as well. If the Melafix does not help, use a product such as Kanaplex or Maracyn. These are broad spectrum antibiotics that you can find in the aquarium section of the local pet or fish store. Follow label directions carefully and remove the carbon filter insert during treatment if indicated. Hopefully, any infection will be resolved with treatment. If it is dropsy, unfortunately, this condition has a high mortality rate.

Thanks for reaching out and including photos. Coeloms (abdomens) are swollen, but unable to determine if eggs. Often when it is time to spawn, the vent becomes slightly everted. An ultrasound would be the only way to truly determine if eggs are in the abdomen. Good luck.

Thanks for providing pictures. Through the pictures, there is a good probability that your fish are gravid and should deliver soon. Hard to tell what species by the pictures (slightly out of focus), but usually with dropsy, the scales rise (pineconing) and the swelling extends more caudally. Dropsy is more a clinical sign and not a disease. Causes include heart, renal, liver or gonadal diseases. There is no one treatment, but depends on the cause. Few are successfully treated, unless a bacterial infection and the proper antibiotics. Hopefully you will have eggs or babies in the next few days.

Thanks for reaching out about Black molly, but a good photo would help. White spots can be infections, parasites, over-active mucus cells, and some other conditions. If the white spot is the anus and is slightly protruding, she could be gravid but maybe intestinal parasites. If concerned, seek the attention of an aquatic veterinarian. Good luck.

Thanks for reaching out about your glowfish. Being gravid can produce distensions on both sides but so can coelomic fluid, an organ enlargement (liver, kidney), constipation and other problems. If having difficulty swimming, eating or isolating self, a veterinary visit is recommended. Good luck.

Mollies do come in gold or orange colorations, but it is difficult to determine from that angle. If you can repost a broadside picture in a new question, that may make identification easier. If it is an egg laying species of fish, the third image could be an egg but I have reservations saying definitively without something for scale. It looks too large to be an egg. As an aside, if you leave the Molly fry in with adults, they will likely be eaten. You can separate the out, remove the adults, use a breeder screen or provide plenty of cover for them.

Not necessarily unfortunately. Abdominal infections, skin oedema, overinflated swimbladder can be common differentials. A check up is required to understand underlying condition and treat appropriately (if treatment is needed). Hope this answer was helpful, but please do not hesitate to contact us again on the forum or by requesting a consultation if you have any more questions or to discuss it any further.