Aquarium fish for beginners: setup, water and feeding
In the first weeks, the biggest danger to aquarium fish is the water itself. How to set up the tank before buying fish, how much to feed, and when to change the water.
An aquarium looks simple: water, fish and food. But fish live inside their water, and anything that builds up in it harms them. Clean, stable water is the most important thing in the tank.
Set up the tank before the fish
- A tank of the right size. Jars and very small tanks get dirty fast and change temperature fast. As a rule of thumb, allow at least 10 litres of water per fish up to 3 cm long, and more as they grow.
- A filter suited to the tank size, and a heater for tropical fish.
- Tap water contains chlorine, which harms fish. Use an aquarium water conditioner, or ask the shop about the right method.
- Keep the tank out of direct sun, so the water doesn't overheat and algae doesn't take over.
"Cycling" a new tank
- Fish produce waste that turns into toxic substances such as ammonia. In a mature tank, good bacteria in the filter turn it into less harmful ones.
- These bacteria take 4 to 6 weeks to build up in a new tank.
- So start with a few fish and add more gradually over weeks, not all at once.
Feeding
- Feed only what they finish in a few minutes. Extra food sinks and fouls the water.
- Fish cope with a day without food better than with dirty water.
- Going away? Ask the shop or a vet about the right solution, rather than dumping in lots of food before you leave.
Changing water and the filter
- Change about a quarter of the water each week, with dechlorinated water at about the same temperature as the tank.
- Don't change all the water at once, and never clean the tank with soap or cleaning products.
- Don't replace all the filter media at once: the good bacteria live there. If it needs cleaning, rinse it in old tank water.
Signs of illness
- Not eating, swimming tilted or upside down, or losing balance.
- Spots, ulcers or growths on the body.
- Gasping at the surface, which can mean a water problem or low oxygen.
If you see these, start with the water: change some of it and check the filter, then ask a specialist shop or a vet who treats fish.