No.
no it is actually good for them
it doesnt depend on gender, they are not poisonous to anything, go ahead and have sushi
NOOOOOoooooo. The oscar would eat the betta fish almost instantly.
only if you've been feeding them poison.
prey
betta are not harmful to people and most tropical fish. However, there are some very common fish that are poisonous. Most of the common plecos with spines can be toxic to tropical fish if they are dumb enough to peck at it. If you feel that another fish you own will get sick from being around your betta, odds are the two can live together happily and healthily. If another pet, like a cat or dog swallowed your betta, I wouldn't worry. I have never heard of pet poisoning from eating tropicals.
BB pellets are not digestible and will create a blockage in the fish resulting in death. The size and the shape of most BB's closely resemble the prepared betta pellets and so could be consumed by accident.
fish or things in the water like sharks,bigger fish stung by eels or by poisonous jellyfish.
Bream are eaten all over the southern part of the United States.
Algae Eaters, 'Mickey Mouse' fish, Platies, Cories, Tetras (Not Neon Tetras though, they will be eaten) Hope that helps!!
other Betta fish and the bigger fish.