for the week of 10/22/98

There are two basic warnings that even most beginning hobbyists have heard: don’t overfeed, and don’t overcrowd. And yet many aquarists, of all levels of experience, have a natural tendency to try to squeeze “just a couple more” fish into their already heavily stocked tanks.

Overcrowding means more maintenance. Common sense dictates that more fish equals more waste equals more filter cleaning and water changing for the aquarist.

Overcrowding leads to declining water quality. Crowded tanks often have low dissolved oxygen levels, declining pH values, high nitrates, and ammonia and/or nitrate levels that rise daily after feedings.

Overcrowding flirts with disaster. No matter what the problem, crowding makes it worse. A power outage that wouldn’t affect a healthy tank’s population can wipe out a crowded tank in an hour. Minor cases of common diseases rapidly become epidemic in the crowded aquarium. An accidental overfeeding can put a crowded tank over the edge.

How many fish is too many? A pretty good rule of thumb is a maximum of a two inch fish for every gallon of water in freshwater, and perhaps half that many in saltwater. Larger fish should also be kept at one inch or less per gallon of water, since waste output and oxygen intake are related to weight, rather than length. Don’t forget to plan ahead, some of those one inch cuties you just bought may someday become 10 inch hulksters.

An alternate method for determining whether or not a tank is crowded is to check water chemistry regularly. If your current tank maintenance routine results in low nitrate levels, zero ammonia and nitrite, high dissolved oxygen and stable pH, then you have a acceptable load of fish.

“Tip of the week” appeared regularly in 1999 and 2000.