First wash all the tank, pumps, pipes, hoses and fittings with a mild bleach solution ( 5 ml household bleach per one litre of water) to sterilise the system to remove any diseases or pathogens. Wear eye protection and plastic or rubber gloves to avoid skin and eye damage. When everything has been cleaned and dried then wash well with plain water.
Connect everything up and fill with the water you are going to rear the fish in, turn on the aerators, heaters and pumps and check that there are no leaks and the pH, temperature, salinity and oxygen levels are at the levels to suit the fish you are going to put in the system.
The biofilter now needs to be conditioned using a nitrifying bacteria culture or you can plan to let your biofilter start working naturally and develop with your fish.
The fish arrive usually in a plastic bag inside a foam box. Take the plastic bag of fish and float it in the tank, carefully open the top of the bag and slowly, over a period of about 30 minutes add water from your system into the bag so that the fish become acclimatised to the new environment.
Slowly lower the bag into your system and let the fish swim out of the bag into the system. The fish will generally be pretty stressed at this stage so expect to see them rush for the bottom of the tank and then stay still for a while.
After a short time they will start moving and exploring but it may be some hours before they are ready to eat any food.
The first few days and weeks are critical and you will need to be doing a lot of checking of the water quality and biofilter to make sure that the system settles in.
As soon as the fish enter the system and you begin to feed then there are waste products produced in the form of fish wastes and uneaten food. A group of bacteria called heterotrophic bacteria will attack these wastes and convert them to ammonia type products.
Small quantities of ammonia products ( 1 part ammonia per million parts of water) in the water are lethal to aquatic organisms.
Fortunately your biofilter will handle this problem so long as there is enough surface area, air and moisture for the biofilter bacteria to live and thrive.
The biofilter bacteria are special and called autotrophic bacteria - they consume ammonia products dissolved in the water and convert them first to nitrite ( also very toxic to aquatic organisms - few parts nitrite per million parts of water ) and then to nitrate which is much safer ( can have up to 400 parts of nitrate per million parts of water for some species of aquatic animals.)
Now some very general rules of thumb
Move the water through the filtration and biofiltration system about once an hour.
Keep the pH within 0.2 points
Keep the temperature wiithin 1 degree Celsius of your selected temperature
Keep the DO ( dissolved oxygen levels ) above 70% saturation
Keep the salinity within 0.1 mS/cm2 (about plus or minus 50 parts per million of your selected level)
Have the biofilter volume equivalent to 20% of the tank volume
Keep the daily feeding rate steady or only alter it slowly
Keep the light levels low
Keep the feeding schedule constant day by day
Exchange 5 - 10 % of the system water per day
Here is a typical starting sequence for some saline fingerlings
The fish arrived in full seawater but the eventual environment was to be saline - about 1/4 seawater or EC 12 mS/cm2 ( 7.5 parts salt per thousand parts of water)
The system was filled with seawater and warmed to 24 degrees Celsius, Aerators switched on, pump switched on and biofilter connected.
Fish in their plastic travelling bag were floated in system tank, bag top opened and during next half hour system water gradually added to bag. Fish then floated out of bag into system. Fish immediately went to bottom of tank and stayed very still. This is a typical shock reaction. After a couple of hours the fish start to explore their new habitat and may respond to a light feed.
For maximum growth the fish need to be fed regularly with a high protein diet. If you have time then feed the fish several times a day until they stop feeding. Keep accurate records so that you can calculate the rate of growth and the food conversion ratio (FCR) - how many grams of feed required for the fish to increase their weight by one gram. As a guide very small fish may consume up to 15% of their bodyweight per day in food. larger fish (150 - 250 gms) may be consuming 5 - 8 % of their bodyweight per day. Larger fish 600 gms upwards may only consume 1 - 2 % of their bodyweight per day. Good fish husbandry is all about knowing your fish and responding quickly to their needs.
There are quick and expensive and slow and cheap ways to get the bacteria in your biofilter growing.
The quick and expensive method is to purchase a good live nitrifying bacteria culture and bacteria food and innoculate your biofilter so that within a couple of days the nitrifying bacteria numbers have grown to handle the ammonia formed in your system.
The slow and cheap method means that you have to let the bacteria populations build up slowly to handle the ammonia load in your system.
BUT both methods require you to take regular (at least daily) readings of your water quality to monitor the development of the bacteria in your biofilter.
What you are looking for is a gradual rise in the TAN (total ammonia nitrogen) with a nil or very low value for nitrite and nitrate. As the TAN level rises you will have to carry out water changes to keep the TAN level below the lethal level for your fish species.
After a couple of weeks (slow method) the TAN level peaks as the nitrite level starts to climb. Again you have to keep water exchanging to keep the nitrite level below the lethal level for your fish. After another couple of weeks the TAN has fallen nicely and the nitrite peaks with the nitrate starting to rise. Again water exchanging will be required to keep the nitrite levels down. Another week or so and the TAN is low, the nitrite is low and the nitrate is rising slowly. At this stage your biofilter is working well.
BUT if you change the number of fish or the amount of food fed or change the water quality parameters then do so slowly - allow the biofilter bacteria time to get used to the new food levels.
The quick method speeds up the process rapidly and allows you to stock your system with more fish quicker. You still have to do the daily water quality monitoring to make sure that TAN, nitrite and nitrate levels go through the same rises, peaks and falls as with the slow system.
Our experience has been that the Nitrosomonas bacteria (the ones that convert ammonia to nitrite) get up and going relatively quickly, however the nitrobacter bacteria (the ones that convert nitrite to nitrate) are much slower to get established so one ends up with a long period where the nitrite levels keep rising and you just have to keep daily water exchanges to keep the nitrite levels within limits for your fish
Regular water quality checks are very important and you should check the following on a daily basis
pH, temperature, salinity, dissolved oxygen, amount of food and feeding times, water taken out, water added, bicarbonate added.
When getting the system started you also need to check DO, TAN, NO2, NO3, CO2, Alkalinity
Changing salinity
Mortalities
Mortalities are an unfortunate fact of life when your experience and equipment are untried. Keep an accurate record of your mortalities, numbers, size, weight, condition and if possible reason for death. Try not to make the same mistake twice. In many case mortalities can be avoided by thinking and planning ahead.
Aquaculture 
