Animated movie/series from 80s or older, where green human-like reptiles fought the good guys, under water I think

I saw an animated movie/series episode in the late 80s early 90s on VHS where two groups of humanlike beings were fighting, I think it was underwater. The bad guys were green and looked a little like reptiles and attacked the good guys with spears. It was pretty serious, and looked like he-man from the animating design. It was a dark film and maybe older than from the 80s. The bad guys won the battle and the others, normal white people, had to retreat to another place if I remember right. And the bad guys had a boss and a second in command, who regurlarly reported to the boss. Does anybody has a guess?

The Flash Gordon animated series from the late 1970s? (I think it was the same company that made He- Man)