Originally Posted by newbie336
I would love to have that many. I was on aqadvisor.com and it said I was overstocked with the fish I listed.
Posted via Mobile Device
The great problem with any calculator to determine fish stocking is that some of the variables cannot possibly be incorporated into the method. "Compatibility" in a community aquarium has several aspects that affect the success (or cause failure) beyond simple numbers.
To take just one aspect, interaction within the group: A group of 3 angels will quite likely cause stress to the angels from the dominant behaviour of one of them. In a group of 5 or 6, this dominance is more evenly spread out, and it is natural; these fish occur in such groups in nature, and it is inherent in their makeup to have this interaction--but not to excess. A group of 3 angels will be under severe stress and this in turn affects the other fish in the tank through chemicals and pheromones released by stressed fish. But in a group of 5-6, this is significantly lessened, resulting in a calmer environment. And that means healthier. So having more fish actually improves the environment. Now, of course one can carry this too far, and the size of tank must always be kept in mind. Plus having live plants helps a great deal because of the "filtration" they perform that no filter we add can match.
Carrying this interaction idea one step further, we add a group of other fish, like one of the rosy tetra. Sometimes this is termed "dither fish" which means these other fish are there partly to calm the angels. This works with almost all cichlids, which on their own can be quite withdrawn and nervous. But a group of peaceful tetra cruising among the plants tells the angels that it is safe to be out and about. By nature, angels are very shy fish, remaining among fallen tree branches, tangled roots, etc., in quite dimly-lit waters. In the relative brightness of our aquarium they do better with companions. Discus are even more like this.
Aquarists seem to frequently forget that fish have evolved over thousands and millions of years to suit their environment. Replicating that environment is a big step in providing a suitable one in the aquarium. A fish like the angel from the habitat I have mentioned, when placed in a relatively bare and brightly-lit tank will always feel threatened. If does not understand that it is under no danger from predators. It only knows what nature has programmed into its instincts, that in such a surrounding it is highly vulnerable and likely to be attacked at any second. This inherent instinct is present in all fish species, and sometimes we see it (as with pale, shivering fish) but often it is not overly-apparent externally. But inwardly the fish is literally terrified. And that means under stress, which means poorer health.
I hope this explains it a bit.