1 neon tetra in 1/2 gallon bowl?

I had 3 neon tetras in a 5 gallon fish tank with my betta, they weren't getting along so i put the 2 neon tetras in the 1/2 gallon bowl..then i decided to put the neons back in the 5 gallon and the betta in the 1/2 gallon. Well, for 3 days the tetras were in the 5 gallon and the filter is a 2-10 gallon filter and sucked 2 of my fish up and they died...now i have one left, i put my betta back in the 5 gallon fish tank and put my 1 neon tetra in the 1/2 gallon bowl...how long will my tetra last?