Throwing a wrench into the mechanics of minimum fish numbers… well, sort of…

[Magnum Man]

But as an enthusiast, we should understand what changes the fish go through… the “general” consensus is “these fish need to be in large shoals”, and I agree with those, as fry / fingerlings, and young juveniles… but psychotic angel fish are a good argument for me, we can’t always have enough of them to prevent the fighting, as they get bigger, or reach sexual maturity… and often they end up as solo center piece fish in tanks, but 6-10 of the 1/2 inch were nice… My Tin Foil’s are a prime example though… I got 5, and as skittish as they were as juveniles, I don’t think I could do less than 5, yet you often see 1 mature fish in larger tanks, with other bigger fish, and they are fine

 

[Magnum Man]

I honestly think we need to look at their spawning type…. Those that group spawn, probably should be kept in a larger shoal… those that pair up, most often can’t be kept in a group past their juvenile stages… I’d bet if I paid attention, there are many fish that pair up, that are still recommended to keep in a decent sized group, from the seller…

 

[CassCats]

The thing with angels is that if you actually look at wild videos, the adults do shoal together. Where we mess up in the hobby is by cramming a shoal inside a tank that's not big enough for a shoal. I run a discord group and talk with several Netherlands hobbyists. They're often ahead of the game there when it comes to care standards... their recommendation for angelfish is a 5 foot+ tank for a shoal to allow them space to both shoal AND pair off to breed in temporary territories. Most folks are cramming them in tanks 4 foot or less and then claim they're "psychotic" because they've gone and killed everything in their spawning space. But, instead, that is on us for not providing them what they require. They're cichlids and cichlids defend a small portion of space when they spawn. They'll defend it from others of their own species and other fish. Given an appropriate space, they can defend this territory without murder, and the rest of the fish still have space to be away from the pair. After spawning they return to the shoal.

If the adults shoal naturally in the wild, they need to be kept the same in captivity.

 

[GaryE]

We usually get started by saying something like: I have a tank in mind. How many fish can I put in it?
We cram in the most we can, and from that, we learn about diseases, aggression and prison behaviour. Since the fish don't "do anything" (they can't), a lot of people quit the hobby. The rest of us move on.
Ideally, in my naive world view, we get to the point where the tank becomes the answer, not the fish. When I see a fish species I'd like to keep, I now won't buy it unless I can say I have a tank for its needs. It sounds simple, but it isn't.
I learned this with Satanoperca daemon, my favourite fish. They aren't shoalers, but to keep them properly, I would argue they need a pair only tank of 8 feet/2.5 m, 200 gall/750 ltr. I own no such tank, and short of winning a lottery, will not own such a tank. So I don't have the fish. I don't care how much I think a pair would be a delight to keep. I can't provide the bare essentials.

I buy fish in bad numbers sometimes. I confess. I have an order put together that I hope to pick up next week, if the fish are still available. All of the tetras are in lots of 10, which is basic. But the Corydoras group fish are in sixes. Why?

Two calculations. One is their price. That's a real issue. Maybe I should buy just one species, and get 12? It's a valid thought.

The other is that they will go into single species tanks and I will do my best to breed them. The fish will be in small groups only if I fail to allow them to build a large group. Only if I breed them will they go into communities.

If I didn't think I could breed them to create a proper shoal, I would buy 12 of one species, and leave it at that.

There are many reasons I have a large fishroom with lots of tanks. It was a money making decision at one point, but I kept the tanks when I didn't keep the job because my curiosity about fish is just too much to ignore. I have lovely room full of resiliconed, repaired and 20 year old tanks. That allows me to keep fish at what I see as proper stocking levels. If I had one tank with my interests, I'd be bored.

I can see @Magnum Man having a similar future, once he retires. The tanks are going to breed. Either the fantastic fish that fascinate him are going to die off from crowding as he goes, or there is going to be a creation of space and a buying of tanks. At that point, with his interests and curiosity, we should be chartering tour buses to go look at the set up. Once the fish he has can cut loose with more space, wow.

I'm very good at spending other people's money... but isn't that what answering questions and getting into fish discussions usually amounts to? We're all trying to run underfunded systems.

 

[gwand]

I think being disciplined is key in this hobby. Easier said than done. I am lucky that I have a great local fish store to rehome fish to when I have a lapse in discipline. At the moment, my five Tanks are understocked. But not by much. I am fighting the strong urge to fill each tank to the brim.