In response to the comments regarding my choice of fish.....Surely there are degrees of happiness. How can we say that certain fish must be kept in groups of 6 or 7. I understand they may be happier in larger groups but they would also be happier swimming in the open water so can we say that we shouldn't keep fish in a tank at all?
Well, that is most definitely an argument against small tanks, sure.. I'll go along with that.. it is the main reason there are a lot of species I really want to keep but have never been able to bring myself to in the aquariums which I have.
We come to that number as the absolute minimum from experience. I have 15 years to offer, I think collectively we have quite some a shockingly large wealth of knowledge. But that's not enough for you? How about.. it has been scientifically observed that fish can count and "panic" when they are on their own. The point we call a minimum for a school (I use 6) is where fish go from "1", "2", "3" to "many". This is the point at which the fish start feeling safe. This is the point where dithers will actually work on nervous cichlids. This is the point where your fish acting in a calm manner, going about their business. This is the point where 1 fish is not able to pick on any specific individual which is lower in the hierarchy than them, this is where there are too many individuals to harass any one or two or other small number.
But, you are right that 6 or 7 is not really a real school, it is only a minimum required to go from "x individuals" to "many". Ideally, no one would keep schooling fish in groups smaller than 15-20 and no one would have ever imagined of putting 20 fish into a 30 litre box, or keeping them in a bare tank..
I understand that a 30L tank is on the small side and maybe I will upgrade one day but as a starter it was all I could justify spending money on. I researched the fish on lots of forums and these were recommended in the numbers I have purchased.
There is a lot of information out there, at the end of the day. I only share my experience with you. You come asking for it? You will get it. You might not like it, you might want more.. that is up to you. Ideally, I would advise only what I would be happy to do myself, but this is not always and option so sometimes I have to even recommend a lesser of two evils if someone is determined not to treat their fish with the same respect they would treat any other pet..
It is up to you to make the choices you think are right, but if you ask on here for experiences of other people, you will get them.
A few years back it was considered fine to keep a single goldfish in a bowl.
Does that make it right?