Introduction to Freshwater Fish
Setting up the tank
Choosing and introducing fish
Once the aquarium is fully prepared and you are certain that everything is functioning properly, you can start to introduce the fish. Although suppliers can ship stock to you, it is probably best to visit a local store, especially when starting out, so that you can see the fish firsthand. Ask experienced aquarists to recommend a store—ideally one that belongs to a recognized trade association. Such bodies run specialized training courses for staff, so you are more likely to receive genuine, professional advice.
Choosing freshwater fish from the vast array available can be a daunting task; a little advance research can help you to make the right choices. Select species that share similar water chemistry requirements, and avoid fish that will quickly outgrow the tank. Temperament and behavior should also be considered; lively, shoaling fish, for example, are not ideal tankmates for species that prefer calmer, less-populated surroundings. Do not mix active predators with smaller, placid fish that could become their prey. Aggressive fish may bully less bold companions and steal their food. Nervous fish, such as some dwarf cichlids, may benefit from the company of “dither” fish— more confident species whose calm presence helps the fish to feel more secure. Finally, try to obtain a mix of species that naturally inhabit different levels of the tank.
Checking for problems
When you have made your choice, ask to inspect the fish to be sure that they are healthy. Before visiting the store, familiarize yourself with the signs of disease in the chart on page 56 so that you know what to look for. It is important to view the fish from both sides, which is easiest to do when it has been caught and is in a plastic bag. It can be difficult to determine the condition of some catfish and other sedentary species, but if they are fairly plump and do not have a hollow-bellied appearance, the likelihood is that they are healthy.
Adding the fish to the tank
Before introducing the fish to the tank, check the water chemistry (see p.46) to make sure that it is suitable for your fish. It is advisable not to populate the tank to its maximum stocking density at first, in order to avoid putting a strain on the filtration system, which will not yet have a fully established colony of beneficial bacteria. Observe the fish closely in these early stages, to make sure that they are settling in peacefully.
The “traffic light” system is used in some aquatic stores to rank sociability.
- A red spot against a fish’s name indicates that it must be kept on its own.
- Yellow means that the fish may have special requirements.
- Green indicates fish that can be kept in a community tank.
INTRODUCING NEW FISH
Being moved can be traumatic for fish, and it takes several days for them to acclimate to their new home. Provide a vitamin C–rich diet at first, to boost the immune systems of the fish and help them avoid stress-related illness.
Equalize water temperatures
- Float the bag in the tank for about an hour, so that the temperature inside the bag gradually adjusts to match that in the tank.
Catch the fish
- Net the fish inside the bag, gripping the neck of the bag to stop water from escaping into the tank, which could introduce disease.
Release the fish
- Carefully allow the fish to swim out of the net. To minimize stress for the new arrivals, do not turn on the tank lights for a while.
CATCHING AND TRANSPORTING FISH
Most fish can be caught with a net. Patience is essential, since chasing the fish around the tank will simply cause them to panic, and the water resistance will make it even more difficult to catch them. Nets can transfer disease between tanks, so dip the net in a solution of aquarium disinfectant after use. Fish with spines should be steered into a bag, because they can become caught up in the mesh of a net. When buying fish, the supplier will catch the fish for you. Fish are usually transported in clear plastic bags, tied at the neck, with a ratio of about two-thirds air to one-third water. Put the plastic bag in a brown paper bag to make the journey less stressful for the fish.
- Neck securely tied during transit
- The store may inflate the bag with oxygen
- Scoop up the fish from below when it is near the surface. As you lift it from the water, place your hand over the net (above) to stop the fish from escaping.