Fish Dying Suddenly

[Danni524]

So, in my 20g, I had a dwarf gourami with five Harlequin Rosboras, a mystery snail, a nerite snail, and an upside down catfish. I lost my dg because he jumped out of the tank and I noticed too late. However, it has been about two to three weeks since then and I haven't added any new fish. Everyone was fine and healthy. Then about a week ago one of the Harlequin passed away suddenly. He was acting fine having fun with his shoal chasing each other a bit. (I think they like all the room now that the DG is gone). Then today, I came home and two were dead. They were fine and alive this morning. They ate their breakfast no problem and went back to "playing."They were all very active before and then all of a sudden dead. I also do a water change once a week and replace about 50% of the water. I do have test strips and they say the Nitrites are 0 and Nitrates between 0-10. I had a master kit, but have to get a new one, but money is a bit on the tight side right now. But because of my water changes and I've had them for a few months and nothing has changed, I'm thinking ammonia poisoning isn't likely. I'm really at a loss at what happened. Also the nerite snail, I've had him about 3 months now and he's starting to slow down and barely move. I think he might be dying as well. It might be illness, but like I said, no fish have been introduced since stocking the tank about fourish months ago and none of them of them are showing any symptoms of anything. Any advice on keeping the remaining guys alive or possible insight to what happened would be greatly appreciated!

 

[SmearingsFish]

Was the rasbora seemingly being attacked at all? Are any other fish in the tank showing signs of illness? Around How long have you had this fish?

 

[Danni524]

Was the rasbora seemingly being attacked at all? Are any other fish in the tank showing signs of illness? Around How long have you had this fish?

No attacks. The only other fish in there with them besides the snails is the upside down catfish, but he stays away from them. All the other fish are seemingly healthy. And the 3 that died weren't acting any different before I found them. I've had them between 3-4 months now.

 

[SmearingsFish]

No attacks. The only other fish in there with them besides the snails is the upside down catfish, but he stays away from them. All the other fish are seemingly healthy. And the 3 that died weren't acting any different before I found them. I've had them between 3-4 months now.

Hmm, gosh. Where did you get them from? And we’re they considered “donation fish?” Sorry to keep asking questions. I’m trying my best to help figure at least something out.

 

[Danni524]

You're fine. Ask away. I'm extremely confused by this situation. I got them from Petco and they were not donation fish.

 

[SmearingsFish]

Thank god they weren’t donations. Haha, they always seem to have issues. If, by chance you remember, were they with other types of fish? And do you quarantine before you add them to your tank?

 

[Danni524]

I think they were in with some type of tetra. I don't totally remember tho. Honestly, this is my first community tank (I usually just keep Bettas) so I didn't even think to quarantine them when I brought them home. Is it possible for them to have an illness from that long ago just now affecting them?

 

[SmearingsFish]

I think they were in with some type of tetra. I don't totally remember tho. Honestly, this is my first community tank (I usually just keep Bettas) so I didn't even think to quarantine them when I brought them home. Is it possible for them to have an illness from that long ago just now affecting them?

very possibly. there are sooo many types of diseases that exist, but just aren’t very well known. Considering (if this is a disease) that there are seemingly no symptoms, I’m really not sure what to do. I’m sorry. Maybe someone else can be of more help.