i have a 20 gallon tank with 1 4inch red tail shark and i added 2 female blue gouramis about a week ago, both about 4 inch and i noticed that one will not let the other leave the corner of the tank and it also once in a while will chase the other around, i was wondering if there was anything i can do for them to be peacefull, i was wondering if maybe adding one or 2 more gouramis would that help and which kind would work best?