That is very strange but maybe being two males/two females makes a difference.sorry for your loss .mine are now over a foot and i believe they are a pair even though there has been no known breeding in captivity,;... they are in full brackish,,, i thought of adding other fish but decided not to,,..these guys are so active that i think it would make any thing else miserable.. they dart with out warning sometimes... they eat everything and they are extremely healthy so why upset the tank anyway...

