I presume you've already sorted this issue out. However, I shall give an alternative for other's who have such issues. First of all having a group of Bettas is a bad bad idea. Specially 2 males and 4 females is even more bad. Whether there are tetras or not the males with fight each other constantly. I've done such experiments in a much larger tank ( a bathtub) and the males fought each other for days on end to establish dominance and one of the males died and was ripped into pieces. ( I wouldn't be surprised if this happens in your case). Normally after such a testosterone filled event the male will go build a bubble nest and will start courting females to lay eggs, here's another problem, this spawning ritual might end up in another ugly war where the male might kill all the females in a quest to save his brood. Male Bettas fish are brilliant fathers and will kill to defend their brood. So I advice you keep them separate.

I presume you've already sorted this issue out. However, I shall give an alternative for other's who have such issues. First of all having a group of Bettas is a bad bad idea. Specially 2 males and 4 females is even more bad. 

Whether there are tetras or not the males with fight each other constantly. I've done such experiments in a much larger tank ( a bathtub) and the males fought each other for days on end to establish dominance and one of the males died and was ripped into pieces. ( I wouldn't be surprised if this happens in your case). 

Normally after such a testosterone filled event the male will go build a bubble nest and will start courting females to lay eggs, here's another problem, this spawning ritual might end up in another ugly war where the male might kill all the females in a quest to save his brood. 

Male Bettas fish are brilliant fathers and will kill to defend their brood. So I advice you keep them separate.

I presume you've already sorted this issue out. However, I shall give an alternative for other's who have such issues. First of all having a group of Bettas is a bad bad idea. Specially 2 males and 4 females is even more bad. Whether there are tetras or not the males with fight each other constantly. I've done such experiments in a much larger tank ( a bathtub) and the males fought each other for days on end to establish dominance and one of the males died and was ripped into pieces. ( I wouldn't be surprised if this happens in your case). Normally after such a testosterone filled event the male will go build a bubble nest and will start courting females to lay eggs, here's another problem, this spawning ritual might end up in another ugly war where the male might kill all the females in a quest to save his brood. Male Bettas fish are brilliant fathers and will kill to defend their brood. So I advice you keep them separate.

I presume you've already sorted this issue out. However, I shall give an alternative for other's who have such issues. First of all having a group of Bettas is a bad bad idea. Specially 2 males and 4 females is even more bad. Whether there are tetras or not the males with fight each other constantly. I've done such experiments in a much larger tank ( a bathtub) and the males fought each other for days on end to establish dominance and one of the males died and was ripped into pieces. ( I wouldn't be surprised if this happens in your case). Normally after such a testosterone filled event the male will go build a bubble nest and will start courting females to lay eggs, here's another problem, this spawning ritual might end up in another ugly war where the male might kill all the females in a quest to save his brood. Male Bettas fish are brilliant fathers and will kill to defend their brood. So I advice you keep them separate.