Hello goldfish lovers! Since I haven’t seen any posts/articles written in English about the use of cocoa powder for goldfish, I thought I’d submit a post. Cocoa powder is used among Japanese goldfish keepers (especially ranchu and pearlscale owners) to treat floatiness due to indigestion, and also for dropsy/pop-eye treatment. Well, it's not a "secret" in Japan - it's widely used, but seems virtually unknown in non-Japanese speaking community. My ranchu’s dropsy was cured using only cocoa powder and nothing else. I don’t know if anyone has done scientific research on this, but maybe the fibre, fat and potassium in cocoa flush out all the nasties in their guts. Maybe something in cocoa inhibit the unwanted bacteria activities, who knows. It worked like magic for me, and didn’t cost me a penny - I already had cocoa in my pantry. Only use pure cocoa powder, with no added sugar or milk, which is usually found on the "baking needs" aisle of a supermarket. The fish will do PLENTY of brown poop like you won’t believe. Here’s how to use cocoa: cocoa balls, cocoa-coated pellets, and cocoa bath. 1. Cocoa balls - add a little water to cocoa powder to make a dough, roll it into tiny balls using your fingertips, leave to dry and feed them to fish in place of their normal diet. Some people mix ground fish pellets to the cocoa to entice the fish to eat them. A fair bit of cocoa may come out through their gills when they are chomping on the balls, but don’t be alarmed, that’s expected. 2. Cocoa-coated pellets are for fussy eaters - soak your usual pellets in a little water, coat the food with a layer of cocoa powder, let them dry and feed them to the fish. Not as effective as cocoa balls, but less likely to be rejected. 3. Cocoa bath is only for use in quarantine tanks. Dissolve a small amount of cocoa powder into the quarantine tank. 1 teaspoon of cocoa in 30 litres (8 gallons) of water seems to be the most common formula. Don’t feed the fish, and don't use a filter. The fish will take the cocoa in while breathing. Let the fish swim (or lie) in the cocoa bath for 2 or 3 days. IMPORTANT: Aerate the tank at all times. You may need to change half of the water and add half of cocoa everyday (or twice a day, depending on your tank setup), as water quality will deteriorate much faster in cocoa bath compared to regular tank water. Not many Japanese fishkeepers use gel food, so I haven’t read about anyone using cocoa-gel in Japan, but that’s what I do. I add some cocoa into gel food. My goldfish love it, and the powder doesn’t spread out into the water like other methods listed above. Hope this helps! PLEAE NOTE: This is a folk remedy. Please use your discretion if you decide to take this on board. I will not be held responsible if your fish gets sick/er or die or your equipment is ruined because of what you’ve tried based on the information found on this post.