In the aquarium hobby there are many myths regarding keeping aquarium fish.

Lets dispel some of these myths and get the truth.

Myth 1: The higher the water temperature the better it is for some species of exotic tropical fish.

High water temperatures reduce the amount of available oxygen if the temperature exceeds 29.C.

This can place stress on the fish in the aquarium over a long term. Also, high temperatures in the aquarium encourages rapid spread of disease pathogens. This means if a fish carries a pathogen, its reproductive capability is greatly enhanced resulting in a disease outbreak.

 A temperature of around 24.C is ideal.

Myth 2: A complete 100% water change is best for the aquarium and fish.

This is a very common misconception about water changes, a lot of hobbyists leave changing the water too long and then do a complete water change. The water chemistry in an aquarium that hasn’t had a water change for months is vastly different to the freshwater. This can shock the fish and lack of oxygen in new water will add further stress to the fish. If the filter is cleaned at the same time, which is the usual practice, this can cause a massive loss of the critical bacteria that purifies the water.

Small frequent water changes are the best practice.

Myth 3: Aquatic plants require dirt or compost.

Aquatic plants derive their nutrients from the water in the form of ions. The fish in the aquarium often create enough ions for most planted aquariums. Some fertilizer additives have trace elements which can be very useful for the growth of aquatic plants. The gravel holds the aquatic plants into place, that’s it. Compost or fertilizer will have little use for the plants and may even cause ammonia to build up which is harmful to the plants.

Aquatic plants derive nothing from the grave or substrate. Good lighting and well filtered water is all that is required. Maybe add some Co2 dosing if you must.

Myth 4: Oxygenation in marine aquariums.

It’s a common belief amongst marine aquarium keepers that oxygen is replenished by the protein skimmer and wave makers. This is not entirely accurate. Protein skimmers will replenish a very minor amount of oxygen, and wave makers only increase the surface area of the water by creating a wave motion.

Its 200 times harder to get oxygen to dissolve in saltwater than freshwater.

Oxygen is only replaced by breaking the meniscus of the water. This requires a violent action such as provided by the venturi outlets, degassing towers or the water falling through the weir to the sump filter.

Circulation alone has no effect.

More myths to be busted next time.