Not the exact events, but saw the attacks going on before finding them. Couldn't see the head anywhere else in the tank. But anyway, AJ kicked the bucket last night. I really think he had the head in his stomach and couldn't pass it. Three tiny Tetra now enjoying 10 gallons.
With my experience with tetras, he would not be able just to swallow the whole head. And they are carnivores, he would easily be able to pass something like that. I would watch your 3 tetras and look for signs of parasites and any disease. Depending on the tetra, you need to get more than just 3, as they school a lot. Some larger tetra species will be "ok" with 3 but prefer more. Id wait a couple weeks and pick up another tank to quarantine some more tetras for your 10 gallon, as its healthy to have as many as are allowed in a tank. I keep neon tetras in my 10 gallon and have kept neons for almost 10 years. They still confuse me sometimes but I have a lot of experience. You want to look out for mainly, NTD, and Ich, and other diseases. Neon tetras especially come from huge breeding farms, and the disease usually passes by the inspectors, that's why when you first get neons, they can be delicate for this reason, but eventually get tougher over time as you feed them and build up their immunity. I have some large neons I picked up at a Pet Smart near me, where 2 of them hit the can the first week, but now all my others are large and tough. With neons the toughest survive. Same with other popular tetras. I do like neons, but in the future I plan on buying Cardinal tetras instead, they are more hardy, look simmilar and arent as over bred in my opinion.