Introduction to Marine Fish
Setting up the tank
Preparing the tank
Assembling the components of the marine aquarium is straightforward, but there are a few important factors, such as the quality of your water supply, that must be considered if you are to achieve a successful result. Patience is vital; even under ideal conditions, it can take several months for conditions in the tank to become stable enough for the most delicate marine species.
When setting up a marine tank, care must be taken not only to create the desired visual effect but also to consider the varied needs of the marine species you wish to keep. Once the substrate has been prepared (see pp.208–209), the next step is to arrange tank decor (see also pp.212–213), taking great care to ensure that it is clean and firmly supported in the aquarium. If necessary, pieces can be held together with silicone sealant, to make them more secure. Arrange the rockwork to contain niches and crevices for the fish to use as retreats. Position rockwork toward the back of the aquarium, leaving a clear swimming area at the front—this will make the fish and other marine life more visible. Live rock (see p.213) should be added only once the tank is full and the water conditions have stabilized.
Heating and filtration components can then be fitted around the rocks. When making your arrangement, be careful not to create “dead spots”—areas where current from the filter does not reach—because uneaten food and debris can accumulate here, which will lead to a gradual deterioration in water quality.
Marine tanks must be filled with a specially prepared salt-andwater mixture (see below). Never use water from the hot-water system in your home; it may be contaminated with copper from the pipework, which can be deadly to invertebrates. Even if using water from the cold-water system, it is always a valuable precaution to test for copper, using a suitable test kit. A further potential problem in some areas is the high level of nitrates present in the domestic water supply. This typically occurs in agricultural areas, where nitrate fertilizers leach through the soil and contaminate the water supply. Test your supply for nitrates, or contact your water company for information. There are various options available for removing nitrates; the simplest is to run the tap water through a special nitrate filter. A reverse osmosis (RO) unit is a more expensive option that removes not only nitrate but also other pollutants, including phosphates. Finally, the water must be treated with a dechlorinator or water conditioner, which neutralizes chlorine and chloramine.
Marine salt is available from aquarium stores and comes with detailed instructions on how to make up a saltwater solution of the correct salinity. It also contains all the key ingredients, notably calcium and magnesium, to ensure that the solution is sufficiently hard, and to enhance its buffering capacity. Salinity is measured on the specific gravity (SG) scale. This compares the density of the salt solution to pure water; the more concentrated the solution, the more dense it is relative to water and the higher the SG reading. Specific gravity can be measured using a hydrometer; the SG reading is taken from the floating hydrometer’s position at the surface of the water.
Once the tank has been filled, the system is ready to be switched on. The thermostatic heater will raise the water temperature gradually to the preset figure.
The maturation process
Coral reefs are very stable environments, and the fish living there are not adapted to significant shifts in water parameters such as temperature, salinity, or water chemistry. In the aquarium, therefore, conditions need to be stabilized before the tank can be stocked with more delicate fish and invertebrates. Before the biological filter is fully functional, levels of ammonia and nitrites can rise to dangerous levels. One way to speed up the maturation process is to introduce hardier species, such as damselfish, into the new tank; these fish can endure the fluctuating water quality, and the waste they produce encourages populations of beneficial bacteria to develop within the biological filter. In addition, cultures of beneficial bacteria are available that can be added to the tank. Regular testing will reveal when the water conditions have stabilized; at this point, ammonia and nitrite levels should be virtually undetectable.
Stocking the tank
A vast range of colorful and interesting species are available today from aquarist suppliers, but it is important to take time to plan and research the numbers and species of fish that are appropriate for your particular setup before you make any purchases. A typical rectangular aquarium can support 1 in (2.5 cm) of fish per 4 gallons (15 liters) of water in the first six months, increasing to 1 in (2.5 cm) of fish per 2 gallons (7.5 liters) thereafter. If you introduce very fast-growing species into the aquarium, however, their eventual size must be taken into account when calculating the stocking density, in order to avoid overstocking problems at a later date.
Make sure the fish you choose are compatible with one another; if you are planning to create a reef tank, check that they will not harm invertebrates. Fish to be introduced should ideally first be quarantined in a separate tank for up to two weeks, to allow any signs of illness to become apparent.
CALCULATING THE VOLUME OF YOUR TANK
To calculate the volume of a rectangular tank, multiply the dimensions of the tank in inches (height x width x depth), then multiply the result by 0.0043 to get the volume of the tank in gallons. If measuring in centimeters, again, multiply the dimensions together, but divide the result by 1,000, to give the volume in liters. Whichever method you use, the final figure must then be reduced by 10 percent, to take account of the rockwork and other decor.
ADDING SESSILE INVERTEBRATES
Before placing sessile invertebrates, such as anemones and corals, in the tank, make sure the rockwork is securely positioned; the delicate bodies of these animals are easily damaged. Position them in a well-lit part of the aquarium and relatively close to a powerhead, where there is a good flow of water that will waft food to them and carry away their waste. Sponges prefer a more shady area in the aquarium. Always transfer these creatures in water to minimize the risk of structural damage, which can lead to bacterial infection.
SETTING UP THE TANK
Special commercial salt mixes make it easy to create the necessary water conditions for a marine tank. It is best to mix the water with the salt before pouring it into the tank so that you can be sure that it is thoroughly dissolved. A second option is to add the salt to a prescribed volume of water in the tank, allowing the filtration system to mix the solution, but it can be harder to be sure that it has dissolved fully.
- Measure the marine salt: Read the instructions on the packaging of the marine salt carefully before you start. Using a measuring cup, pour out the appropriate amount of salt.
- Prepare the saltwater solution: Measure out the required volume of water in a watering can or bucket, and treat it with a dechlorinator before slowly stirring in the salt with a wooden spoon.
- Build up the decor: Add rockwork and other basic decor to the dry tank. First create a secure base with larger rocks, and then build up the rockwork, leaving plenty of holes and crevices.
- Fill the tank: Place a clean saucer on the substrate and then carefully pour the salt and water solution onto it, to avoid disrupting the base layers of substrate in the tank.
- Measure salinity: Check the salinity of the water using an instrument that measures specific gravity, such as this hydrometer.
INTRODUCING THE FISH
Wait for a few days after setting up the tank before obtaining and introducing the first few hardy fish, to be sure that the system is functioning properly. When choosing a fish for your tank, always ask the supplier to let you examine it closely; carefully inspect both sides of its body for any signs of illness or injury. Also ask to see the fish feeding, because this is a good guide to its general state of health. The supplier will catch your chosen fish and transfer it to a plastic bag; it should be kept here for the minimum possible time before introducing it to the tank.
- Equalize water temperatures: Float the bag in the aquarium for about 15 minutes. This allows the temperature in the bag to slowly rise to match that in the tank, thus minimizing the stress on the fish.
- Catch the fish: Net the fish inside the plastic bag, being careful that the water in the bag, which may contain medication or harmful microbes, does not spill into the tank.
- Release the fish: Allow the fish to swim out of the net and into the tank. Newly introduced fish will often hide away at first, retreating into crevices in the rockwork.