This grouping thing

[peathenster]

Some fish are supposed to "do better in a small group (e.g. 6)", like clown loaches, fronts, juruparis, etc etc.

Is it mostly because of 1) breeding issues; 2) they are seen as groups in the wild or 3) there will be problems when they are kept alone (if so, what problems)?

Need to decide soon whether to expand my two jurupari "group" to six...they do get big!

 

[cichlid2006]

some fish can get stressed if not kept in a group, some like most loaches are very social and form a hierarchy. there is always the odd "social" fish that will like being kept alone. i have read about a rogue clown loach killing other clowns that were put in to be company.
some fish will survive fine but may be less active and quite shy if kept alone. and they may even be skittish, silver/bala sharks are known to be very skittish when kept alone and can often cause themselves harm from smashing into the glass or decor in a tank while fleeing.
eventually being kept alone can lead to a shortened life span as the fish may be unhappy and prone to common ailments such as fungus and fin rot, which over time the repeated illness leads to shorter life.

ive never witnessed these effects on a lone social fish as ive always kept social fish in groups so this info is all from books and internet readings.

 

[darth pike]

Interesting note from Fishbase about Satanoperca group activity:

Discourages piranha attacks by watching the predator, a tactic used when 2-5 fish feed in groups and the individuals take turns as the "watchman". Confronts an approaching piranha by charging towards the predator with an open mouth and erect dorsal fin.

 

[peathenster]

Very interesting. Based on both of the replies (thanks!) I guess they may watch each other's back and hence feel safe in a group....better get some more juruparis then...will be a sight in a few month when they grow up!