In a 500g tank an aggressive mala is likely to calm down.Also depends on the temperament of the wolf. Some are bad mofos some are very docile. I'd check the wolf first before getting anything
Highly doubt it'd bother a soul in some of the monster set ups some members have on this site.My mala is an absolute stone cold killer. Once he gets full size there is no way he would be suitable for any tankmates in any size tank.