Reference
Reference
This page explains, in plain language, the words you need to follow any conversation about aquariums. The definitions are short and don't claim scientific completeness: their job is to help you read instructions, species profiles and advice from experienced fishkeepers with confidence.
Clear water doesn't mean clean water. The substances most dangerous to fish are invisible, so a fishkeeper relies not on their eyes but on understanding what is happening inside.
Water
- Nitrogen cycle
- A chain of changes in which fish waste and leftover food produce ammonia, and beneficial bacteria turn it first into nitrite and then into nitrate.
- Ammonia
- A substance produced from waste and rotting food. It is toxic to fish, which is why its build-up in an aquarium is especially dangerous.
- Nitrite
- An intermediate product of the nitrogen cycle, made when bacteria convert ammonia. Also toxic to fish.
- Nitrate
- The end product of the nitrogen cycle. Less toxic than ammonia and nitrite, but it gradually builds up and is removed by regular water changes.
- Water change
- Regularly replacing part of the aquarium water with fresh, prepared water. It helps remove accumulated substances without upsetting the established balance.
- Water conditioner
- A product for treating tap water. It is needed above all for chloramine, which doesn't leave when water is left to stand.
Equipment
- Filter
- A device that pushes water through a sponge or other media. Besides mechanical cleaning, it serves as a home for the beneficial bacteria of the nitrogen cycle.
- Heater
- A device that keeps the temperature steady. Not every species needs one, and the level of heating is matched to the needs of the particular inhabitants.
- Lighting
- The lamp above the aquarium that plants need and that sets the fish's daily rhythm. Leaving it on too long often leads to algae overgrowth.
- Substrate
- Sand, gravel or special substrate on the bottom. Plants root in it and bacteria live in it, while waste settles on it and is removed with a gravel vacuum.
Inhabitants
- Compatibility
- The ability of species to live in one aquarium without harming each other. It depends on size, temperament and water requirements.
- Quarantine
- Keeping new fish, snails or plants apart from the main aquarium for a while, to spot any disease in time and avoid passing it to the others.
- Schooling fish
- Species that live in groups in the wild and get stressed when kept alone. They are kept in a small school of their own kind.
- Invasive species
- An organism that ends up in a habitat foreign to it and pushes out native wildlife. Released aquarium fish, snails and plants can become invasive and spread disease.
Where these words come in handy
- Guides
A step-by-step article on doing a water change without stressing your fish, plus the article catalogue.
- Questions
Short answers about tap water, which fish get along, everyday care and the first signs of trouble.
- Sections
Four big topics: water and the nitrogen cycle, equipment, aquarium inhabitants and regular care.
- Collections
Reading paths: your first month with an aquarium, an aquarium with a child, plants and snails.
Read next
- Questions
Short answers about tap water, which fish get along, everyday care and the first signs of trouble.
- Guides
A step-by-step article on doing a water change without stressing your fish, plus the article catalogue.
- New
A feed of new guide pages with dates, topics and a note on who will find each one useful.
Sources
- Beginner fishkeeping handbooks
- Materials on biological invasions
Information is current as of the date this page was prepared. Fish, plants and invertebrates vary widely in their needs, so before buying a new animal, always check the requirements of that particular species.