What are possible reasons for sudden death of Betta?

[Emily in Everett]

We had a betta inexplicably die today. Looking for possible reasons as I don't want it to happen again!

Purchased a male crowntail betta from Aquarium Coop about 4 weeks ago, along with 2 aquatic frogs. Frogs and betta placed in established, planted 5 gallon tank. We had a previous Betta live there happily for 2 years until he suffered from swim bladder issues. We've changed no parameters or routines for the new betta/frogs except to add bloodworms to the daily food to make the frogs happy, and set the temp to 78 instead of 82.

Betta seemed normal for 3 weeks. During last week betta has been hiding/sitting still a lot which was unusual. Today seen hanging upside down letting the gentle filter flow suck him up to the filter inlet. If rousted he swam fine but kept wanting to end up upside down lodged in plants, breathing hard. 2 hrs later he was floating on top dead. No signs of parasites, bloating, ich, pokey scales, or anything. Looks perfectly healthy. 

All I can figure is:

• Parasite it (or the frogs) came with?
• Ate too many bloodworms? (though there was no sign of overeating nor did we observe it, and the frogs did a good job of limiting the betta's access to the worms once they floated to the tank bottom)
• Somehow got physically hurt?
• RFD (random fish death) that I just must accept.

Could there be any other likely causes?

Tank parameters at time of death and at all times in previous 2 years: filtration (gentle flow), regular small doses of Flourish fertilizer liquid and equilibrium powder to keep the plants happy. 30-40% water changes and gravel vacuuming every 1-2 weeks. PH 6.6-6.8, Nitrates usually 5ish, never above 10, nitrites always 0, hardness: softish, kh lowish.  Bettas have been fed Aqueon betta pellets; frogs get frozen bloodworms of which the latest betta also gets a few before the frogs chase him off. I'm fairly experienced at keeping tanks healthy, with some really stable 15 and 90 gallon tanks and I've gone through the new tank owner routine with all the nitrite/fungus/ich etc. lessons that come with that. Heat has been 78 for this betta/frog combo; it was 82 for the previous 2-year-betta.

Any ideas?

 

 

 

 

 

 

Edited April 19, 2022 by Emily in Everett

[Fish Folk]

Very sorry to hear! I confess to having a hard time with certain Bettas . . . others, no problems.

My first _guess_ is bloodworms. If your Betta was unable to pass them through GI, that could have brought on a little "perfect storm" of other related issues, perhaps affecting swim bladder.

But that's just a guess. I do feed blood worms most days of the week, but also balance with greens and shellfish to help food pass smoothly.

Perhaps he injured himself, and when relaxed, lost control of functions -- leaving him belly up, as you describe? I've never kept frogs, so I couldn't say one way or another if they're in any way a contributing factor.

Very sorry to hear though. 

[Emily in Everett]

I suppose the overeating option might be possible. The previous betta got occasional brine shimp, and the issues started around the same time we tried offering him some brine shrimp and may have put too many pieces in the water. 

[Wrencher_Scott]

Fish die all the time for no apparent reason. I bet it was just sick for some reason that wasn't your fault.