| Re: Swordtail with internal trouble
Hey Rick,
Actually there is a possibility that your fish was not pushing out its guts as white poop could be a sign of a few problems. Perhaps the easiest to address would be to ensure that you are feeding your fish the right types of foods. Because fish tend to have specialized digestive tracts, they are unlike humans in that many will become 'sick' if their diet is too heavy in meats and/or veggies. IMO, your fish may also benefit from an occasional dose of fiber (many people might feed a smashed pea to their fish...sometimes waiting a day or two to help ensure the fish are hungry enough to try it) and a lot of hobbyists - myself included - have enjoyed the benefits of using a garlic supplement to promote internal health.
Another possibility is an internal parasite such as Hexamita; although I am not 100% sure how common this particular problem might be in swordtails. In short, Hexamita is a parasite that attacks a fish's intestines (lower ones I believe), resulting in the fish expelling white, sometimes slimy/bloody "poop". In the case of internal parasites/illnesses, as far as I know it is always suggested to provide medicines/treatments that your fish would ingest (eat) versus treating the water alone. Garlic supplements may also have a positive effect for your fish if it/they are suffering from an intestinal parasite and can also be used as an effective preventative measure as well. | 
I am sure that others might also have some better advice for you as well so hopefully you can avoid the same problems later on...right
