A comment (or two) on the issues raised in the several posts concerning rams and puffers.
I certainly acknowledge that there is often some quite variable opinions around the hobby over many issues, and today with the easy access to the internet one can find all of these being put forth by many people. One has to consider the source of such material in order to weigh its reliability.
The behaviour of a fish is programmed into it by nature, over thousands and even millions of years. Some fish within a particular species may exhibit behaviours that are outside the "normal" for the species. This can occur due to environmental stimuli--very peaceful fish for example can become quite nasty in the wrong environment. And by environment I mean water parameters (hardness, pH, temperature), tank size, aquascaping (something natural to the fish or something foreign to it), numbers of the species, other species unsuitable in the same space, filter currents, and intensity of lighting. All these can and do affect the fish in the aquarium, positively or negatively, depending.
On the rams in particular. There is ample scientific evidence to support the most widely accepted opinions on proper maintenance. Mikrogeophagus ramirezi is territorial. Given sufficient space for the males to establish a reasonable territory in the aquarium, and several may do quite well in that tank. But the smaller the space, the fewer rams can be housed if one is concerned over their health. Stress caused by constantly battling each other takes its toll by weakening the fish's immune system, and this opens the door to various health issues that will lead to a shorter lifespan.
Mikrogeophagus altispinosus (Bolivian Ram) occurs in solitude in its natural habitat. In other words, individual fish far apart, generally interacting only when spawning. To subject a group of these fish to the confines of a small aquarium is, frankly, irresponsible. The stress from this situation is bound to take a toll on the fish.
A 180 litre/48 gallon aquarium that is 3 feet in length will not provide sufficient space for more than 2 males in the case of M. ramirezi, and only one with M. altispinosus. A couple of females with one male would work. But a group of 8 would not.
Byron.
Similar Threads 
