ok this may help...When mature, male tiger barbs will show bright red noses, his dorsal fin will have a red line above the mainly black fin and his ventral fins will turn bright red. When in spawning condition or fighting for a higher “rank” in the shoal, the males stripes turn a slight metallic green colour. And the tips to his upper body scales turn almost black and shine bright orange in certain light.
The females however, keep their pale yellow noses (may turn slightly pale red at times, which makes it tricky to determine their sex in store). They only show a small area of red at the tip of the dorsal fins, and ventral fins will stay pale red. In females, their stripes stay black.