Bloated fish, not pregnant and not worms

[Jean Feil]

So, I have a 20g long tank with 8 live bearers and 1 betta in it. That is, I did up until this morning. I woke up to find that one of my guppies (born in this tank on 11/11/19) and a baby platy (born in this tank on 3/30/20) were dead. Yesterday they were fine, other than being bloated for a few days. The platy was a female, so I thought she might be pregnant, but the baby platy was a male.

Though it made me sick to do it, I sliced them open and there were no worms. So, if they were not pregnant and not full of worms, what could have caused the bloating and what killed them?

Other tank members, besides the betta:

2 guppies (born 11/11/19 and 12/20/19)
1 molly (born sometime in late 2018)
2 mollies (purchased on 4/1/20)
1 platy (purchased 1/25/20)
2 Zebra Nerites

Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 20ppm (a little high, which is weird because I do weekly 30% water changes on Sundays and today is only Thursday)

Tank is moderately planted.
Nothing new added to the tank recently.
And no, the betta didn't kill them. He's afraid of his own shadow and he's also been in there with them for months.

One of the other guppies looks bloated, too. I'd love to find out what happened so I can prevent her from dying, too.

Thank you!
Jean

 

[PheonixKingZ]

Bloating usually indicates internal worms. @Colin_T will be able to help you.

 

[Colin_T]

Pictures of the fish?

If the fish stop eating and are bloating up overnight, they have an internal bacterial infection and there isn't much you can do.

Intestinal worms only cause fish to get really fat if there are lots and lots of worms in the fish. Worms normally cause the fish to lose weight.

 

[Salty&Onion]

Bloating usually indicates internal worms. @Colin_T will be able to help you.

And bettas, no matter what, are not community fish. I'd get a spare 5-10 gallon tank with filter and heater for him or give him back to the store.

 

[PheonixKingZ]

And bettas, no matter what, are not community fish. I'd get a spare 5-10 gallon tank with filter and heater for him or give him back to the store.

I agree. Bettas aren’t community fish and shouldn’t be kept as such.

 

[Salty&Onion]

I agree. Bettas aren’t community fish and shouldn’t be kept as such.

I did keep my lil Candy with other fish, but I'm more experienced, but anyway bettas should not be kept in community tanks no matter what.

 

[PheonixKingZ]

I did keep my lil Candy with other fish, but I'm more experienced, but anyway bettas should not be kept in community tanks no matter what.

In all of the cases that I’ve kept fish with my old betta, the other fish ended up causes problems (fin nipping), not the betta.

But as you said, it is not recommend for beginners to keep bettas with other fish.

 

[Jean Feil]

Pictures of the fish?

If the fish stop eating and are bloating up overnight, they have an internal bacterial infection and there isn't much you can do.

Intestinal worms only cause fish to get really fat if there are lots and lots of worms in the fish. Worms normally cause the fish to lose weight.

I have already disposed of the dead fish. Here is a picture of the dead guppy's sister. She is not quite as bloated as the one that died.

The fish didn't lose their appetites. They were swimming and eating just fine as of yesterday, but I did fast them last night because I wasn't sure what was going on. They eat Aqueon Tropical Flakes.

I have two platys in my other 20g long that are super bloated, too. I was hoping THEY were pregnant, but now I'm doubtful.

 

[PheonixKingZ]

Do you have any males in the tank?

 

[Salty&Onion]

In all of the cases that I’ve kept fish with my old betta, the other fish ended up causes problems (fin nipping), not the betta.

But as you said, it is not recommend for beginners to keep bettas with other fish.

I never had a single problem with Candy and his tank mates, and I am experienced in this case, but keeping bettas with community fish, even female bettas is not recommended to begginers.

 

[Jean Feil]

Do you have any males in the tank?

 

[Colin_T]

The guppy looks pregnant/ gravid.
The platy looks a bit off colour, maybe gill flukes. 2 heaped tablespoons of salt per 20 litres of water for 4 weeks will treat that.

The only reasons fish will get fat is from too much food or they are carrying eggs or fry. If a fish is eating well and bloats up overnight and dies, then it is usually organ failure (liver or another internal organ) that has failed or been damaged. Bacterial infections are the most common cause of internal organ failure.

------------------
If a fish ever gets sick, wipe the inside of the glass down. Do a 75% water change and gravel clean the substrate every day for a week. Make sure any new water is free of chlorine/ chloramine before it's added to the tank. And clean the filter.

Doing these things will dilute any disease organisms in the water (assuming there is any), and it will help clean the conditions up and give the remaining fish more chance of fighting off whatever is causing the problem.

 

[Salty&Onion]

I'd get a spare 5-10 gallon with filter and heater for the betta or return him to the store as bettas aren't community fish no matter what, this has been mentioned in previous posts.
We need to know your water hardness which can be found on your local water providers website. What is the tank size?

 

[Jean Feil]

The guppy looks pregnant/ gravid.

Thanks Colin. Yes, I was really thinking the dead guppy was pregnant. She had an even bigger gravid spot. But when I sliced her open, I saw no fry and no worms.

 

[Salty&Onion]

The fry might not have developed yet and these must have been eggs, and maybe that's why you did not see any fry.