Even among clown loaches arguments might occur. Sometimes real fights take place. The typical "knuck knuck" sounds are increasingly produced in such situations. Just listen to it after feeding!
It is interesting that argueing fish slightly change their colour. Orange blanches and black becomes grey. So far I don't know the biological reason for this yet.
You can see a pale clown loach on the picture on the right side.
Clown loaches are very sensitive animals. Every change in their environment means stress to them. Especially after moving in, it is really important to have enough hiding opportunities for clown loaches. Clown loaches won't show up that often in the beginning and will hide as soon someone comes closer to the aquarium. After a while the fish get used to their environment and common movements. Sometimes they become downright confiding and eat out of your hand.
Clown loaches are very peaceful fish and can be associated with most of all other fish species. So far, I could not recognize any aggressive behaviour - however, this still should be possible for single cases.
A clown loach is not a real schooling fish, but should be kept in a large group - this in turn presupposes a bigger tank. Groups from five to six animals should be seen as a minimum. The larger the clown loach crowd the more fun it is too watch them! Only in groups those fish can properly develop. Hiding options are always important to offer a peaceful place in case of arguments.
A group of clown loaches forms a hierarchy which is usually lead by the largest animal. In some literature it can be read that the most senior male leads the pack. As you cannot define a clown loaches' gender for sure, (apart from dissecting the fish), it can be questioned, if it must be the male. You can get a glimpse of the hierarchy while feeding and also while fish organize their habitat. Additionally, I could observe that the smallest animal is often sent ahead to explore the environment - for example if the animals have recognized movement around their aquarium. Only later - if there is no danger - the rest of the pack appears, too.