Depending on the species, bloating in aquarium fish is often an indication that a fish is pregnant. A pregnant female will often have a bulge in her belly 20 to 40 days after mating, whereas a fish that has been overfed may be simply getting fat.
Why do my fish keep getting diseases? ›
Many of the disorders and diseases that are known to occur in fish are the result of stress, poor water quality, overcrowding, and failure to quarantine any new or sick fish to avoid spread of disease.