For the past few days I've noticed my fish, Ciel, become increasingly sluggish. Today he was pretty much at the bottom of his tank the whole day, barely moving unless I tapped on the glass (to make sure he was still capable of moving). This is what he looks like now. He is in a topfin 3.5 gallon tank which is filtered and has a heater to maintain the right temperature. His water was changed today after a month and I put in stress coat+ to condition the water. The only thing I could think of that caused this is that I hadn't thoroughly cleaned his tank until today. He's always been fine without water changes for a month or so (which I know should be done every week) but I think some food pellets that he didn't eat sank to the bottom under the pebbles and began to rot which gave him an infection? Today I completely rinsed out his tank, scrubbed off all the grime on the tank and the decor with a sponge, and meticulously made sure that every single pebble in his tank was completely clean. I then had to leave for nearly 5 hours and I come back to him still being at the bottom of his tank. What can I do? He's only 2 years old and he's always been a truly healthy fish with such a personality and would dance every time I gave him food. Now he doesn't even want to come to the top of his tank to eat his pellets, he's just laying there breathing and barely even moving his pectoral fins.
He looks to have dropsy. It's not a sickness but a symptom. Once the symptoms of dropsy appear, the fish has a very low chance of surviving and thriving as dropsy is due to kidney/organ failure and liquid build up. Maintaining clean water is probably your best option to him surviving. Some people have used Epsom salt baths to help them regulate the liquid in their body
There's a page on Dropsy Treatment under the disease section, I recommend following that. You'll need kanaplex and unscented epsom salts. I'm sorry about your betta, one thing I will say is that complete water changes are stressful to fish, and I highly recommend reading up on the nitrogen cycle. That being said, the full cleaning itself probably wasn't enough to cause this. Good luck.
