Bettas mysteriously die, noticing white mouths later.

[Xeek]

Sounds like there's no hope.

What about the crayfish? "I would never put that crayfish back into any tank ever again ever?" Why are you saying this? This is a passive species of crayfish and a very small one too. Not much bigger than ghost shrimp. You blame the crayfish?

[paloverde]

No I don't blame the crayfish, He could could spread the plague because he was in the tank. He could always be kept in a species only tank and you would need to be so very careful to not share any equipment. I know it's really sad news.

[Xeek]

So you are saying he carried this and spread it? I didn't see the evidence to your sudden assumption.

[paloverde]

I don't know how the plague entered your tank? It could have come in on live plants or fish or yes the crayfish, if he had been in a tank that had the plague. It is a vicious disease and is spread by contact via the water or occupants and it moves fast as you well know.

[Xeek]

So there is no treatment other than letting the fish die and disinfecting the entire tank and tossing all plants? Really?

[Xeek]

I didn't get much help here. While I have surviving fish I am not going to kill them all and take down this tank.

I am going to try Tetracycline. I will not try salt though as the corydoras can't handle that. I've also read better referenced articles that show salt does not help. Tetracycline seems to work though not everyone seems to suggest or talk about it.

[lexylex0526]

Originally Posted by Xeek

I didn't get much help here. While I have surviving fish I am not going to kill them all and take down this tank.

I am going to try Tetracycline. I will not try salt though as the corydoras can't handle that. I've also read better referenced articles that show salt does not help. Tetracycline seems to work though not everyone seems to suggest or talk about it.

READ MY FIRST RESPONSE!!
Thats how to treat it!

[paloverde]

I truly hope that your treatment is a success, and if it does cure them please post back how you did it.

[Xeek]

Originally Posted by lexylex0526

READ MY FIRST RESPONSE!!
Thats how to treat it!

You method was partially a good idea. My fish were acclimated to that pH a long time ago. Bettas have no problem with this pH. That's not the problem. These fish were kept in other tanks with the same specs on water.

Treating with salt is a bad idea with catfish. Treating with copper will most likely kill my crayfish and catfish. Doing all this and adding antibiotics - I'm just making my tank an industrial chemical tank and not a fish tank.

The antibiotics though seem like the wisest choice.

[bahamut285]

Originally Posted by Xeek

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Ammonia: 0
Nitrite: 0
Nitrate: ~0
pH: 8.0
Hardness: 0 dGH (Don't have a KH test)
Alkalinity: Unsure

This doesn't bother anybody else?

If you are noticing the white stuff AFTER death, it is probably just fungal decomposition. If they are getting it before death, then it is probably columnaris.

I'd be more concerned about your water parameters. Where are you getting your water from? It looks like it's being run through a R/O unit or a water softener. Without replenishing natural ions in the water, it's not good for fish or even people to drink. (Essentially this sounds like distilled water)

With a hardness of 0 dGH, there are little or no natural nutrients in your aquarium for your fish to live on (stuff like iron, magnesium, etc.) that both your fish and you as a human need to live. Your KH is probably low as well, which will give rise to pH swings.

Your pH of 8 is fine as long as it stays like that. I've had fish live in pH of 8.2 at my apartment at school.