16'' males. they are aggressive but each fish is different. I had mine in with 2 gold sevs, 2 oscars and a pleco and they did fine. I removed sevs and added a festae , mayan, and a female jag. no major fights but plenty of flare ups. it was only a matter of time before I figured the jags paired off so I put them alone in a 75g. that was 4 mos ago. I've seen some jags bang glass at fish across the room and people . just mean. I've also seen them in community tanks albeit larger tanks 150 and up. tankmates should be aggressive if any.