I don't see fish as being problems except during breeding (some damsels will wreck house), moreso problem aqurists (you could view cichlids, tetras, wrasses, tangs, angelfish, etc. in the same light as they all tend to behave aggressively towards others). There is no such thing as peaceful aquariums, a misnomer, as everything is under a check & balance system and the smaller the tank the more likely incidents will occur. As with anything, most problems could be avoided if researched ahead of time
*try talbot damsels, they are lovely and rather passive for a damsel XD
*try talbot damsels, they are lovely and rather passive for a damsel XD