Both sick fish are dead. That black spot grew to cover nearly half of the side of the fish within about 12 hours of appearing and he was dead. The other died of dropsy as has every crowntail that I have had. The last fish is still perfectly healthy. Pet store few towns over had what they called a fish expert and she said the black spot was columnaris and to watch the healthy fish for few weeks because that’s apparently fairly contagious. My tank is always kept clean and the fish feed every evening. I’ve never heard of or been told to test the water before.
I have 3 bettas that have lived in separate but joined tanks for about 6 months. The water is filtered and flows from one tank to the next and then back through the filter. 2 of the fish are sick. One has dropsy and is starting to pinecone. Is there anyway to save this fish? The other fish is lethargic and simply won’t eat. He is getting thin. His fins are ragged and have been since he got full size (almost 5months ago) so I’m not sure if that’s a sign of rot or not. He was a fluorescent white when I bought him but then turned a deep blue and now is turning white again except for a tiny black spot on one side towards the back. His gills appear clear and unclogged and he doesn’t seem to be having trouble breathing. Does anyone have any ideas on what is wrong with this fish? The fish are in separate spaces now with no shared water and the one fish is still perfectly healthy.