Betta killed 2 neon tetras

My Betta killed 2 neon tetras but after watching the tank closely it seems they were mistaking his fins for fish flakes. I read somewhere that tetras will nip other tetras fins if they’re in a big enough school. I only have four now and was wondering if I should add more since they do best in bigger schools and maybe they will leave the betta alone if there is more of them. There’s been no hostile interactions in about two days and the tetras have learnt to avoid the betta. The betta also never goes near them unless they one is separated from the group so was also thinking that if there was a bigger school then neither would interact with eachother. Also all fish in the aquarium have been in for 3 days and it is a 12 gallon aquarium housing 1 betta male, 4 neon tetras, 2 Amano shrimp and 2 ancistrus. Any help is appreciated

 

A 12 gallon is too small for a neons and much too small for one, not even two bristlenose plecos. It was likely a territorial attack. It will not get better by adding more; if you want to add more you should transfer just the neons to at least a 20 long.

 

Killing fish is a definant sign the betta does not want to play well with others. Like getting smacked upside the head with a 2 x 4 obvious sign.

 

I'm afraid Cue is correct about the overstocking, but perhaps like many here, you'll succumb to MTS (multi-tank-syndrome) & remove everybody but the betta to a larger tank. With the set up Cue suggests, you'll be better able to appreciate your neons schooling & your BN will have more surface area in which to forage. Your fish will have more of what they need in properly sized tanks.

As for your betta, I wouldn't hold my breath hoping there will be no more aggression. In my experience, it's unlikely your neons are provoking the betta into attack. Higher numbers won't change that. It's more likely your betta is separating out & weakening individual tank mates until he can deliver the death blow. Your neons, if they're crowding & nipping him, are likely acting defensively. Very simply, bettas are predators. I have seen bettas successfully integrated into community tanks but only in large tanks, heavily planted, with lots of hides, broken up sight lines & the right betta. It sounds like your betta isn't one of the gentle rarities that has little desire to hunt. Essentially, you're keeping neons as feeder fish for the betta.

If you're commited to that betta, you may do best by returning the remaining neons & the two BN to the fish store. Then you can focus on building a fabulous tank for the betta! Alternately, if you want only one tank & you prefer the neons & BN, buy a minimum 20g, preferably long as suggested by Cue & return the betta. The BN really shouldn't be housed in anything smaller to keep them healthy & long lived.

Sorry to be the bearer of bad news - but hey - if you're willing & able to get that 2nd tank, you might *really* enjoy the new aquarium adventures & then it'd be good news! In any case, you'd have support here whilst building up whichever tank(s) you choose. Welcome to Fishlore.

 

If your tank is at least like 50cm-60cm long I'd just keep the betta and get some more neons. If the betta still attacks them than you'll probably have to move him but more neons should help with the fin nipping since they'll be less stressed with higher numbers.

 

You are correct that schooling fish do better in larger numbers, but you also have to consider their other needs, like a lot of space to swim in. Putting more neons in a tank that is too small for them is not a good plan to decrease stress. The BNPs need to be rehomed. 12 gal is too small for even one. If you want to decrease stress, you can dim the lights and add a lot of plants while providing plenty of open water at the same time.

There a beta keepers here who will hopefully weigh in.

If you buy sick fish again just return them and have them replaced. Better yet, stay away from that shop.

 

Betta keeper here, but a bit of a noob. I have a 10 gallon and was obsessed with a community set up for my betta. I settled on getting a mystery snail, some ghost shrimp, and 7 green neon tetras. Once I added the neons the betta chased them, was too slow, and gave up.

Everything was peaceful but when I woke up the next morning, the bettas fins were tattered. I wasn't sure if this was due to water quality dipping after adding the fish or stress, so I did a 10% WC and added stress zyme. Sat next to the tank and started studying for my final on my desk, look over and betta is missing a new chunk of fins. Neons were nibbling on him when my back was turned. They were returned and betta is now healing nicely with his new more friendly nerite friend.

Long story but I'm now a firm believer that at least green neons and bettas in such a tank are a no go. I can't even imagine having regular neons in that set up as they are bigger. Do yourself a favor and leave the 12 gallon for the betta and shrimp as they are more beautiful to watch when they're stress free and maybe return the neons and BN or get them a larger tank as suggested above.

It's hard to give up that tank size for one fish but it's much nicer to look at one happy betta than multiple unhappy fish.