In general we have found that stability of the environment is the most important secret to successful fish keeping. A lot of material has been written about the ideal environment for various species of fish, whether they like warm water or cold water, high Ph or low Ph, hard water or soft water, but this is generally useful only if you are attempting to breed the fish or are planning on keeping a very sensitive fish that is known to be challenging. In choosing all of the items and the fish themselves, always keep in mind the stability of the environment. Don’t be fooled into thinking that the smaller the aquarium the easier it will be. Actually, the larger the aquarium is the more stable it will be and the easier it will be to maintain healthy fish. The amount of oxygen available (which is critical to fish survival) is determined mainly by the amount of surface area of the aquarium (not just the size) since oxygen enters the water primarily at the surface. Although aeration, with an air stone or a power head, seems like it is directly adding oxygen to the water, most of the benefit comes from moving water from the bottom of the aquarium to the surface where oxygen is exchanged for carbon dioxide. THANKS…