I have recently received a possibly sick veil-tail betta from someone. What I know about the betta is that he lived in a thin 1 gallon tank, without a heater, no filtration system, used tap water without any conditioners. He had lived in this environment for about 4-5 years.
I asked to take care of him because he looked ill and I wanted to give him a better life overall. His fins were brown and somewhat translucent, and the inexperienced owner wasn't concerned. Though I admit, I am not well experienced at maintaining a healthy tank environment, nor have much knowledge of fish diseases but I'm trying to learn.
Here are some pictures of the betta right after I first received him.
I bought Jungle Fungus Clear after reading about the symptoms of fungus. I believed him to have clamped fins and fin rot, and tarnish on his head, so I thought to give it a try.
Here's something that may or may not be a problem. After putting in a Jungle Fungus Clear tablet, a translucent string appeared, rising from the bottom to the top of the water, and it had a black tip, and not sure of its origin. Perhaps it was from the tablet but I thought it was weird. I recorded a short video of it here.
Currently, he has a 5 gallon tank all to himself, using Seachem Prime tap water conditioner, with a filtration system with low water current, a Tetra 2-15 gallon heater with a constant water temperature of 78 degrees fahrenheit, keeping check with a thermometer, along with aquarium salt. And following directions with anything I put in the tank. The water has been quite clear so far. And I plan on doing regular water and gravel maintenance when it's time.
Other than his appearance, he swims around like a healthy fish and eats TetraMin Flakes regularly. The water current is completely new to him so he got pushed around by it at first but seems to have gotten used to it, and he seems to have much better movement control over his fins and body than before.
I'm writing here in hopes that someone can identify his problem, if any, and just not from old age. And to give me any useful advice, or to point out any mistakes I have possibly made.