Do parasites die off if the tank does not have any fish?

[Swiftwater]

I had a 15 gallon and was using a betta to cycle it, then I noticed that he had a parasite that would only come out at night and it was in his head and one of his eyes. I tried giving him a salt bath twice but the parasite doesn't die, I've been thinking about keeping him in my 2.5 gallon for life. The parasite looks like an anchor worm but it doesn't branch off like a y its just a straight line.

So I was wondering if the parasite laid eggs and I left the 15 gallon without any fish for like 2 weeks, would they die on its own if they could not find any hosts?

 

[Pyramid_Party]

Not familiar with these type of parasite, but I think so, because other parasites like ich die this way. But I would suggest raising the temp really high too, like 90-100 that will kill off most parasites. But to be sure, I think you should get a 2nd opinion on this too.

 

[Lupin]

If it is anchorworm, carefully pluck it off with tweezers. Do lots of water changes until the wounds heal completely as it is likely secondary infections can happen and harm the fish. Read the sticky thread for parasites.