3 sudden deaths in 5 days?

[rsh]

I have a 29 gallon tank that had a Mollie, a Betta, a Platy, and several Platy fry in a contained net to grow. 
I bought two male guppies on Sunday and by Monday, one of them died. I thought it could’ve been eaten by the betta because its tail wasn’t in tact, but the next day, the betta was dead. 
I checked the water parameters and everything came back in a normal range (except I have hard water) and went and got my ammonia levels checked which also came back safe. 
I did a full water change and added fish back to the tank and all was well until this morning when another guppy died. 
 

I’m kind of at a loss as to what could be killing off my fish all of a sudden, in 7 months only one of my 6 fish had died, and now I’ve had 3 in one week. Any ideas?

[JosiahBass]

Was there any kind of damage to the fish, if not. My guess would be a parasite or some sort of disease.If you could give me more information on the the fish and how they look after they died I could help you more.

[Tony s]

Just a couple quick things. Hard water for you is going to be perfectly normal. 85 % of the US has it. The fish you have actually do really well in hard water. Second, your betta wouldn’t bother with those fish. I have 7 bettas, all in community tanks with those fish. Bettas are usually only aggressive towards other bettas. 
 

You may have something going on. Hard to tell at this point. Could have been a temporary ammonia spike. Or it could be nothing at all. Just coincidence. Guppies and bettas purchased at big box pet stores can be relatively hard to keep alive. Bettas for me only last 6 months to a couple of years. They can receive some harsh treatment before purchasing. Out of the ones I have kept only 1 has made it to 2 years. But I keep rescuing them, better than living their lives in cups. Their tank mates are still fine. Guppies from pet stores can have poor genetics due to extreme line breeding. And some handling concerns. 

 

[jwcarlson]

It's really difficult to say what might have caused the problem.  Do you have any pictures?  Sometimes that might help.

I'm only bringing this up because no one else has yet, but this is a great example of why quarantine is very important.  If you'd have QT'd the new fish and they died in QT... no big deal as that's what QT is for.  If you QT'd and you still lost fish in the existing tank then at least you'd know that it was just a timing thing.  But having it happen in your main tank right after adding new fish and seemingly spread an issue to other fish makes it really hard to pinpoint on account of all of the variables here.  I'm not trying to pile on or anything, this is just a good example of how it complicates troubleshooting issues when you don't QT.  

Small fish can have very small problems that are exceedingly difficult to see, so I'd suggest taking a good long look at everyone left in the tank.

[rsh]

On 2/23/2024 at 9:01 AM, JosiahBass said:

Was there any kind of damage to the fish, if not. My guess would be a parasite or some sort of disease.If you could give me more information on the the fish and how they look after they died I could help you more.

Both guppies had their tails chewed and all three fish were laying on the bottom of the tank (in the same spot) on their backs or sides and they were curved 

On 2/23/2024 at 11:19 AM, jwcarlson said:

It's really difficult to say what might have caused the problem.  Do you have any pictures?  Sometimes that might help.

I'm only bringing this up because no one else has yet, but this is a great example of why quarantine is very important.  If you'd have QT'd the new fish and they died in QT... no big deal as that's what QT is for.  If you QT'd and you still lost fish in the existing tank then at least you'd know that it was just a timing thing.  But having it happen in your main tank right after adding new fish and seemingly spread an issue to other fish makes it really hard to pinpoint on account of all of the variables here.  I'm not trying to pile on or anything, this is just a good example of how it complicates troubleshooting issues when you don't QT.  

Small fish can have very small problems that are exceedingly difficult to see, so I'd suggest taking a good long look at everyone left in the tank.

I don’t have any pictures unfortunately, and none of the now dead fish were in quarantine when they died. They all acted normal and just died suddenly so I didn’t notice anything wrong to quarantine them. I’ll look at the rest and see if I can see anything!

[Tony s]

bent spines? could be the genetics. chewed tails? I've never seen a betta go after platys or guppies before. I have bettas with both 

 

But... You could have had a mean betta

Edited February 23 by Tony s

[JosiahBass]

On 2/23/2024 at 12:33 PM, rsh said:

Both guppies had their tails chewed and all three fish were laying on the bottom of the tank (in the same spot) on their backs or sides and they were curved 

If it looked like the Image attached it is Fin rot. Otherwise I would say that there was a fight and your guppies lost. If you think it is fin rot I can give you some advice on how to make sure none of your other fish get it. Are any of your living fish fins damaged.                                         

[JosiahBass]

Here is something that can help you if it is fin rot.