Summary

There are numerous water chemistry parameters in the aquarium that need to be monitored. Those primarily concerned with keeping rainbowfishes are dissolved oxygen, temperature, pH, alkalinity and carbon dioxide. However, many dissolved substances, which cannot be measured by the average hobbyist, rapidly accumulate in an aquarium especially if the water is not changed on a regular schedule. These dissolved substances remain largely unidentified but include organic acids, sugars, microbes, phenolics, proteins, hormones and fine particles of detritus. The toxicity of these dissolved substances to rainbowfishes is not completely known; however research has indicated that certain components will inhibit the growth and development of rainbowfishes and increases their susceptibility to disease. Some researchers believe that there is a direct relationship between high levels of these substances and high populations of disease organisms in aquaria.

A variable proportion of these accumulated substances is readily degradable and consumes significant amounts of oxygen, increasing carbon dioxide levels, lowering the pH, and contributing towards the deterioration of water quality. Therefore the reduction of these compounds ultimately leads to improved water quality and healthier specimens. Only regular waterchanges will lower the concentration of these substances and restore a stable environment. The more frequently the water is changed, the lower the stresses on the system and its inhabitants. Most rainbowfishes enjoy waterchanges; they seem stimulated by them, so long as they do not involve so great a change in water parameters that they induce stress.