Hard to tell the difference unless they pair up. Especially when they eat a lot as they get fat. Just some personal guest male have more pointed head and a bit longer snout while female are a bit fatter.
mine's not eating well... left some feeder golfishes in there with it.... but dun seemed to see a buldging tummy... with me for ard 1.5 weeks ...
but very aggresive towards 1 of my emperor, so had to give it away before the argus killed it...