Help! Guppies Dying One By One (Photo)

[Falconfree]

Hi, my guppy tank has been having issues for a few months now, as my adult guppies have been dying off one by one.

They will be listless and floating near the intake the night before, and in the morning they'll be dead. I've lost 4. This started after the 55 gallon tank they were in cracked, and I moved them into a 20 long, with the same gravel and filter (a canister filter for 75 gallon tank, so I turned the out go down a little in such a smaller tank).

The water parameters are 0 ammonia and 0 nitrite, 20 ppm nitrate. Low PH.
The tank is medium to heavily planted, no decorations.

There are 2 female guppies, 2 male guppies, 2 nerite snails, and maybe a couple dozen little guppy fry. I know it is overstocked (or will be soon), our local pet store says they are having a tank sale soon so I'm hoping to get another big tank.

I started treating the tank with salt (1/2 tsp per gallon twice a day for 3 days, per a guppy ailments website). Yesterday was day 3. One of the girls is swimming oddly today, like she is tail heavy. Her gills also look a little red. Ideas?

 

[Falconfree]

Oh, and the tank is heated to 77 degrees. This is also the first of the guppies that has exhibited this bent spine look. It is possible the rest did it sometime during the night, since they all died during the night though.

 

[tanker]

Low PH? Guppys like a higher PH. What is low?

 

[Falconfree]

I know they prefer higher, but it sounded like they are pretty adaptable. Is that not right? Most the places I read said messing with low Ph is more trouble than it is worth. I use the API master test kit, and it comes back 6.0. It is also fairly hard. Dang Florida water. :/

Another adult guppy is now exhibiting a bent spine too (his has always bent slightly bent, but it is worse as of tonight). He also appeared to have a tiny red spot on his tail, but I couldn't get a good look.

 

[tanker]

6 is way to low for guppys, 7 is much better. The bent spine is not caused by your PH though.

 

[Tifftastic]

The gills look red to me and the fins appear a bit tattered. I don't think treating with that low an amount of salt is really going to help much. You should be upping it to about a tbls/5 gallons to get any value out of a salt treatment. My first thought is Mycobacterium. We recently had an infection of this in some of our zebra fish and they had the same symptoms. Its basically present in all freshwater aquaria but when the fish get stressed they can be open to attack, the sudden move caused by the crack in the tank would seem like a likely source of the initial stress. We had some luck with kanamyacin, but you could also try tetracycline. Don't even try penacillin as it is so overused in the US (fish farms) that most freshwater bacteria are resistant to it. But that would be my best guess.

 

[Falconfree]

Her fins were like that when I got her, they've actually been looking a little better. I should have mentioned that, since you can see it in the pic. I'll go pick up some more salt and antibiotics. Thanks!

 

[Falconfree]

Well, all the fish in the tank have died, as of yesterday. I tried Kanaplex + Sulfaplex, and Prazipro, just in case it was an internal parasite. The fish looked slightly better after a couple days of the antibiotics, but about a week later started declining again (while still on ABX).

The idea of having to throw out all my plants in this tank makes me want to cry. No local fish store here, and Petsmart plants here look awful, so I have to ship them in. Additionally, what about my nerite snails? They look well, but I wouldn't want to accidentally spread myco to another tank by moving them. Can snails be infected with myco?

What would you do?