This is a common misconception. It is actually water quality that stunts growth in fish, not the size of the aquarium. Since nitrates and other pollutants, which act as growth inhibitors, accumulate more rapidly and to higher concentrations in smaller aquariums, they have a greater impact on fish growth and health in small aquariums. Providing proper filtration and performing frequent partial water exchanges will maximize growth and health in your fish regardless of aquarium size.
A general rule of thumb is one inch of adult fish per net gallon of water, but activity level, territoriality, available habitat and filtration should also be taken into account. Remember, the average aquarium holds less water than its designated size once gravel and decorations are added. (For example, a fully decorated 10 gallon aquarium holds about 8 gallons of actual water). In addition, most fish that are purchased are going to grow, and some fish just need more personal space, so plan ahead. Always consult an aquarium expert when adding new fish to your aquarium.
Feeding depends on the type of fish you own. Aside from large predatory fish, most aquarium fish do best when fed only what they can consume in 2 minutes or less, once or twice a day. Any leftover food will pollute the water and stress your fish. Herbivorous (vegetarian) fish need to eat more frequently, but still feed only small amounts per feeding. Many experienced aquarists skip feeding their fish once or twice a week to allow them to clear their digestive systems.
Water changes dilute toxins that naturally accumulate in the aquarium. There are many philosophies about frequency and volume, but small water exchanges done frequently are generally considered best for maintaining healthy conditions in your aquarium. A 10% water exchange done weekly is ideal, however, changing about 25% of the aquarium water once or twice a month is sufficient for most aquariums. Avoid changing more than 50% of the water in your aquarium. In doing so you can dramatically change the aquarium water parameters (temperature, pH, chemistry). Major changes to the aquarium environment should be done slowly so fish have time to acclimate.
Filled aquariums weigh approximately 10 lbs. per gallon. For example, a 20 gallon aquarium will weigh about 200 lbs. once filled with fish, substrate, décor and water. Most household furniture will likely only support aquariums of 5 gallons or less. Aquariums that are larger than that should be placed on a stand or base manufactured specifically for aquarium use and designed to safely withstand the weight of a filled aquarium.
The duration of light needed in will vary. Aquariums with artificial décor need 8 to 10 hours of light per day, however, aquariums containing live plants will need about 12 to 15 hours of high quality light per day. Hours of light should be the same each day as fish rely on a daily rhythm for their activity and proper health. Use a timer to provide a consistent day/night cycle. Avoid placing an aquarium in sunny location or leaving the light on all the time as it can cause extreme algae growth.
Algae is nature’s way of purifying water and grows when there is an abundance of nutrients (from fish waste) and light. To keep algae to a minimum, provide good filtration, feed your fish sparingly, do frequent but small partial water exchanges and avoid excessive light from windows or leaving the aquarium light on too long. Algae eating fish like plecostomus, otocinclus and flying foxes will also help keep your aquarium algae under control.
There are different views on this, but in general, as long as rocks are sterilized and are not calcium based, you can put them in your aquarium. Scrub them thoroughly and either boil or soak them in a mild bleach solution – rinsing thoroughly afterward before placing them in your aquarium. Calcium based rocks are usually white in color and may raise pH and alkalinity to unsafe levels. They should only be used in African cichlid aquariums. To find out if a rock is calcium based, place a few drops of white vinegar on it; if it fizzes, the rock is probably calcium based.
Newly set up aquariums may turn cloudy because of a biological imbalance and will usually clear in a few days if left alone. Do not add any new fish or do any cleaning of the aquarium or filter. Established aquariums can turn cloudy because of overfeeding, too many fish or inadequate filtration. Adding a larger or second filter, removing some fish and/or cutting back on the amount of food entering the aquarium will often resolve this problem.
There are a variety of filter options, depending on the situation. The most common are hang-on-back, internals or canisters. Typically, hang-on-back filters work well for beginning aquarists with aquariums of 90 gallons or less. They provide all three types of filtration in one unit – mechanical, biological and chemical – and are very user friendly. Internal filters are for smaller aquariums 40 gallons or less. They are economical filters that are placed inside the aquarium for a cleaner look. They also provide all three types of filtration but are usually not as powerful as hang-on-back units. Canister filters are well suited for aquariums 50 gallons and larger and do not require cleaning as often. Aquariums with messy fish should have good mechanical filtration, while heavily populated aquariums should have additional biological media. If looking to improve filter performance, select a filter rated one size above the actual aquarium size.
Glass tanks are more durable and do not scratch easily, providing a clearer view inside the aquarium. They are heavier in weight and require an aquarium furniture stand that is built to withstand the weight of a filled aquarium for a long period of time. Acrylic tanks scratch more easily and can potentially yellow over time. Aqueon acrylic aquariums are commonly 10 gallons or less so they are lighter in weight and are suitable a tabletop or counter. Acrylic aquariums are also available in a wider range of shapes than glass aquariums.
Fish don’t have eyelids to close, but they do go into a state of rest and reduced metabolism at night, so yes most fish do sleep. Some fish even settle to the bottom at night, and can be picked up by hand. Others remain on alert for danger while in “sleep” mode. Fish that need to keep swimming to breathe, like certain species of sharks, as well as blind cave fish, never sleep.
Actually, the process of “cycling” does not begin until fish or a culture of nitrifying bacteria are added to an aquarium, but the longer you wait to add the first fish after initially setting up your tank, the better. Most aquarium experts recommend waiting at least 48 to 72 hours. Always check temperature and test for pH and ammonia first, as many municipalities add chloramine to tap water and a single dose of water conditioner does not always fully neutralize the ammonia.
Most tropical fish do best between 76° and 80° F. Discus, wild caught angelfish, uaru and certain other fish that are found at or near the equator do better at temperatures between 84° and 88° F. Goldfish, koi and other coldwater fish prefer the temperature between 65° and 72° F. Research the particular fish before determining what temperature to keep the aquarium.
New livestock purchases should be slowly acclimated to the temperature and water chemistry of your aquarium. Turn off the aquarium light and float the bag containing new fish inside your aquarium for 15 minutes to equalize temperature. Keep the bag closed during this process. After 15 minutes, open the bag, roll the top edge down a few times to form a floatation ring and add a small amount of aquarium water to the bag. Continue adding small amounts of aquarium water to the bag every 5 minutes. After 20 to 30 minutes, gently net the fish out and place them in their new home. Discard the water from the bag, do not pour it into your aquarium. Leave the tank light off for an hour or two to allow the new fish to get used to their new home. An alternate method is to place new fish with their shipping water in a clean container and drip water from your aquarium into the container using air hose and a plastic control valve. Drip rate should range from 1 to 2 drops per second for small bags to a slow dribble for larger bags. After 20 to 30 minutes, gently net the fish out and place them in your aquarium. Leave the tank light off for an hour or two to allow the new fish to get used to their new home.