Small nano aquariums are all the rage in the local fish stores (LFS), but when it comes to fish aquariums, the bigger the aquarium the better. The sales staff at most LFSs are trained to encourage customers to buy as big a fish aquarium as possible, and there is good reason for this.
Among the list of factors that are important in keeping freshwater or saltwater fish in glass houses, providing our fish with consistent water conditions is up at the top. Wherever fish are found in the wild, the water they are swimming in stays the same from day-to-day in terms of pH and temperature. Even when conditions do vary, as with the rainy season in either the Amazon or Southeast Asia, the changes are gradual. Besides pH and temperature being constant, ammonia, nitrite and nitrate (three important values we need to monitor in our aquariums, as they are all deadly to fish in varying amounts) are not a problem in the wild. The primary factor that contributes to the consistency of water conditions is the sheer volume of water that fish in the wild live in. The waters of the rivers and lakes our fish come from is immense – and we keep our fish in 10-gallon aquariums!
Put quite simply, there is more margin for error with a large fish aquarium as opposed to a small one. Keeping fish healthy and happy in a fish aquarium is a constant battle against pollution. If you think about it for a moment, you will realize that fish live in their own toilets. Add to that the fact that most hobbyists feed their fish too much fish food, keep the lights on for too long, or simply neglect their fish aquariums. The smaller the aquarium is the bigger the problems are when it comes to errors in fish husbandry. In small aquariums pH can crash quickly, nuisance algae can take over in a matter of days, and one dead fish can send the ammonia readings off the chart – all with disastrous consequences. The larger the fish aquarium the less deadly these problems are and the fish have a better chance of surviving our mistakes. The cost is not unbearable to move up from a 15-gallon to a 20-gallon high, or from a 20-gallon long to a 29-gallon. Your fish will thank you in the long run.