Setting up your first freshwater aquarium in Japan
A freshwater aquarium is one of the more forgiving pet-keeping setups if the initial steps are done in the right order. The most common reason first tanks fail is stocking fish before the biological filter has established, a process called cycling. In Japan, tap water quality varies significantly by region, which adds a local variable worth understanding before you fill the tank.
The nitrogen cycle and why it cannot be skipped
Fish waste produces ammonia. Ammonia is toxic to fish at concentrations above approximately 0.5 mg/L. Beneficial bacteria (primarily Nitrosomonas and Nitrobacter species) convert ammonia first to nitrite, then to nitrate, which is far less toxic and removed by partial water changes. Establishing this bacterial colony takes three to six weeks in a new tank.
Cycling can be done with or without fish. Fishless cycling, using a small amount of ammonia added directly to the water, is less stressful and produces a more bacterial colony before any animals are introduced. We recommend this approach for first-time keepers.
- Add dechlorinated water and run the filter for 24 hours before adding anything.
- Introduce a small, measured amount of ammonia (2-4 mg/L target).
- Test ammonia and nitrite every two to three days.
- The cycle is complete when ammonia and nitrite both read zero within 24 hours of an ammonia dose.
- Perform a 50% water change before adding fish.
Water quality in Gifu Prefecture
Gifu City tap water is moderately soft, with a general hardness (GH) typically in the range of 3-5 dGH and a pH around 7.0-7.4. This is suitable for several commonly kept species, including tetras, rasboras, corydoras catfish, and most livebearers. It is not ideal for species that require very hard, alkaline water, such as African cichlids.
Chloramine is used in some municipal water supplies in Japan rather than chlorine. Standard dechlorinators neutralise chlorine but not chloramine. Check the label of your dechlorinator to confirm it handles both, or use a product specifically labelled for chloramine removal.
Stocking density and compatible species
A common starting point is one centimetre of adult fish body length per litre of water, though this is a rough guide rather than a rule. A 30-litre tank can comfortably support a small school of neon tetras (six to eight fish) alongside two or three corydoras catfish. Adding more species too quickly is the second most common cause of early tank failure after skipping the cycle.
The aquarium starter guidance session at Solar Pioneer covers all of this in 30 minutes and includes a look at the live plants and beginner fish we currently have in stock.