Let your fish tell you if its over stocked. keep an eye on your nitrate, nitrites and ammonia, if the latter two stay zero and your water changes keep nitrates low then you fish will be your indicator. If they are not being aggressive toward eachother and they have safe places in the tank arent showing signs of stress, then leave it alone. Dont add anything else, but if that jag is a male and gets larger, thats when you may have to worry. I'd also pay attention to your hop, if its aggressive it could be a problem too