Betta Fish Died Very Suddenly

Our approximately one-year-old Crowntail Betta died very suddenly. We are still in shock. He appeared happy and healthy last night when we went to bed. He was an extremely active betta with a healthy appetite. We woke up this morning and he was dead at the bottom of the tank and already partially consumed by some of the snails in the tank, showing the white flesh of his body under his blue scales. Given the level of scale loss from what I assume was the snails, I would guess he had been dead for several hours, meaning he went from being active to dead in just a few hours.

There were no signs of deadly disease on the body that I could see, including no signs of dropsy.

Water parameters are excellent (Ammonia - 0, nitrites - 0, nitrates - 10, pH - 8.2) and he enjoyed a cycled, heated (79 degrees), planted 10-gallon tank with an HOB filter (set to low flow) and a sponge filter.
I had just done a 30% water change with a gravel vacuum), which was typical.
Tank inhabitants include two freshwater limpits, three small mystery snails, some “pest” snails, and nine CPDs.

About six days ago, we introduced six adolescent CPDs (I’ll call them Batch 3). Before this latest batch, we had bought six adolescent CPDs to join our lone adult CPD (Batch 2), who was the last of the last batch we had (Batch 1). Three of the Batch 2 CPDs died within a day or two, as did the remaining adult CPD from Batch 1. The six from Batch 3 and the remaining 3 from Batch 2 look healthy.

My only thought is that the CPDs from Batch 2 or 3 brought a bacterial infection that killed our Betta. But he showed NO SIGNS of infection or disease. I have never had a betta die so quickly, and all of the ones I have had in the past that died from dropsy or columnaris showed outward signs of disease and hung on for several days.

Any thoughts on what could have killed a strong healthy young betta so quickly? We are heartbroken over this loss.

 

Only things i have off-hand are a)did you remember to chlorinate the new water on the water change? And b)maybe introduced something to the tank on your hands (i.e. soap, lotion, etc)

 

Only things i have off-hand are a)did you remember to chlorinate the new water on the water change? And b)maybe introduced something to the tank on your hands (i.e. soap, lotion, etc)

My sister thought that might have happened, too. I recall adding Prime to the water, and I have a Wondershell in the tank for the snails, which also helps dechlorinate water. It’s entirely possible that a chemical or something was introduced to the water, but none of the other fish or snails seem to be affected.

I’m starting to wonder if he had a heart attack or stroke. Can that happen to a fish? They have cardiovascular systems.

 

Unless you want to do get a microscope and do full necropsies on your fish be happy with "You did the best you could". Not every creature will live to a ripe old age even in perfect conditions and there will be outliers above and below the predicted life expectancy. For bettas the range is usually given as 2 to 5 years and male bettas can already be 1 year old when you get them.

 

Yeah, I suppose at this point, it doesn’t matter. I am treating the tank for a bacterial infection, just in case, because I think there’s a strong possibility that a very fast-acting bacteria took him down overnight. I don’t want the other fish to succumb to it, if that’s what it is. Given that we’ve lost a few CPDs over the last 2-3 weeks, maybe we ignored a big warning sign.