Articles
On planning, cycling and caring for an aquarium, on plants, disease and salt water: the short version first, and checked against the sources.
Planning
Before you buy an aquarium4 min read
What an aquarium costs in time and money, where it should go, and why a bigger tank is easier than a small one.
Choose fish that suit your water4 min read
What GH, KH and pH mean in practice, why tap water varies so much from place to place, and how to find fish that thrive in yours.
How many fish can I keep?4 min read
Why "one cm of fish per liter" falls short, and what adult size, schools, territory and swimming zones mean for how many fish a tank can hold.
Fish that get along4 min read
Temperament, fin nippers, fish that eat other fish, and fish that need the same water. And what the Harmony mark in the app means.
The equipment you need3 min read
Filter, heater, thermometer, light, test kits and water conditioner: what you need from the start, and what can wait.
Substrate and decor4 min read
Gravel or sand, how deep the substrate should be, how to rinse it, and rocks and wood that change the water.
Setting up and cycling
Cycling: the nitrogen cycle explained4 min read
Why fish die in new tanks, what happens in the water during the first few weeks, and how to tell when your tank is ready.
Fishless cycling4 min read
Step by step: how to cycle a new tank before the fish move in, how long it takes, and how to speed it up.
How to add new fish4 min read
From the store to the tank: how to get the fish used to your water, why you should add only a few at a time, and what to watch for in the first few days.
Quarantine for new fish3 min read
Why new fish should live in a tank of their own for a few weeks before they move in, what you need, and what to look for.
Everyday care
Water changes: how much and how often3 min read
The most important thing you do for your fish each week: how much water to change, how to vacuum the gravel, and what the new water needs.
Feeding: less is more3 min read
How much and how often to feed your fish, why overfeeding is so dangerous, and food for bottom dwellers and herbivores.
How to test your water3 min read
Liquid tests or strips, which values matter and when, and how to log them in the app.
Cleaning the filter3 min read
How to keep the filter clean without killing the bacteria that do the work: tank water, never tap water, and never everything at once.
Vacation: what do I do with my fish?4 min read
Adult fish do just fine for a few days without food. How to get your tank ready before you leave, and why vacation feeder blocks and automatic feeders can do more harm than good.
Plants
How to care for aquarium plants3 min read
Light, nutrients and CO₂ in balance, low tech versus high tech, and how to read from the leaves what your plants are missing.
Easy plants for beginners4 min read
Plants that cope with low light, soft water and a beginner’s mistakes, and how to plant them so they grow.
Lighting: how long and how bright3 min read
How many hours the light should be on, why more light does not mean better plants, and how to avoid algae.
Aquascaping
Biotope aquariums: a slice of nature4 min read
What a biotope aquarium is, how to build one after a particular river or lake, and how the app helps you find species that belong together.
How to set up a South American aquarium4 min read
Soft, acidic water, subdued light, sand, roots and fallen leaves: how to set up a biotope aquarium from the Amazon and the rivers around it.
How to set up a Central American aquarium5 min read
Hard, alkaline water, sand and rock: an aquarium from the rivers and lakes of Mexico and Central America, with cichlids and livebearers.
How to set up an African aquarium5 min read
Two completely different aquariums: forest rivers with soft, brown water, roots and leaves, and Rift Valley lake cichlids in hard, alkaline water with big rock piles.
How to set up an Asian aquarium5 min read
Two aquariums from Southeast Asia: calm forest streams and peat swamps with soft, brown water, and fast mountain streams with cool, oxygen-rich water.
How to set up an aquarium from Australia and New Guinea4 min read
The home of rainbowfish: water, substrate, plants and light for rainbowfish, blue-eyes and peacock gudgeons, with a long aquarium and open water in the middle.
How to set up a North American aquarium5 min read
Streams and ponds in North America are often cool. How to set up an aquarium without a heater, with pygmy sunfish, shiners and darters.
How to set up a European aquarium5 min read
A coldwater aquarium with European fish and plants, without a heater. The water follows the seasons, and summer heat is the biggest problem.
Problems
Algae: which kind and what to do3 min read
The most common algae in the aquarium, how to recognize them, and why the cause is almost always an imbalance of light and nutrients.
Cloudy water3 min read
A white haze, green water or murky water after a move: what makes the water cloudy, and what to do about it.
Fish gasping at the surface3 min read
When your fish hang at the surface gulping for air: the most common causes, and what to do right away.
Snails that multiply3 min read
Where the little snails come from, why lots of snails often means too much food, and how to bring their numbers down without poison.
Fish diseases
Sick fish: how to spot it and what to do first3 min read
The signs that a fish is not doing well, why you always test the water first, and what to do before you buy medicine.
Ich (white spot)4 min read
The most common disease in aquarium fish. How to recognize it, why it shows up, and how to get rid of it.
Fin rot and columnaris4 min read
Bacteria that attack the fins, mouth and skin, nearly always after poor water. When water changes are enough, and when more is needed.
Velvet and dropsy4 min read
Velvet is a fast-moving parasite. Dropsy is a sign that something is seriously wrong inside the fish. How to recognize them, and what you can do.
When a fish has to be put down3 min read
When it is right to put a fish down, how to do it quickly and gently as the Norwegian Food Safety Authority describes, and what to do with it afterward.
