cherry barb

Just admiring how my cherry barbs like to be in the watersprite.

Something is different since yesterday: Sangre has changed color. He is usually rather pale, pinkish body flushed around the edges. I worried for a long time that he was anemic or had ammonia poisoning- the red on fins looked streaky- but then figured it was normal and forgot about it (other barbs in pics online have similar pinkish hue). Today suddenly after the water change he is nearly brick-red like the smaller males. I wonder if he's in breeding mood again with the refreshment of new water?

(The very next day, Sangre was pink again. Pretty sure he was responding to the water change).