Getting Started: The Tank and the Salmon
The first thing you need to do is determine which type of system best suits your classroom situation and what type of salmon you will raise.
Which tank is right for you?
Selecting a Tank System
There are basically three types of tank systems: Closed, Open and Semi-open. Each has advantages and disadvantages.
The Closed Tank System
This is similar to a traditional classroom tropical fish tank. Water is carried in buckets from the nearest tap.
Closed System Advantages
You can put this tank almost anywhere.
It does not require special plumbing arrangements.
As they monitor the tank's water chemistry, children will see clearly how fish affect their environment and how the environment affects the fish.
Closed System Disadvantages
You will be hauling a lot of water in buckets.
The Open Tank System
This tank is plumbed into a dedicated water line and drains into its own sink. An activated carbon cartridge removes chlorine from incoming water.
Open System Advantages
This tank cleans itself automatically.
You never have to haul water in buckets.
Open System Disadvantages
It requires special plumbing arrangements.
A true open system tank is economically feasible only when your tap water has no substances (other than chlorine) which are harmful to salmon.
The tank keeps itself so clean that students may not see as clearly how the fish affect the environment and how the environment affects the fish.
The Semi-open Tank System
This tank is plumbed into a dedicated water line and drains into its own sink. Incoming tap water is filtered by an activated carbon cartridge to remove chlorine and by an ion exchange cartridge to remove metal ions. Set up and materials for Open and Semi-open systems are virtually identical. For more information on this, contact the manager of the Washington State Salmon in the Classroom program.
Semi-open System Advantages
To clean this tank, you simply siphon water into the sink below it. The tank refills itself after you clean it.
You never have to haul water in buckets.
The metal removing filter makes it possible to raise salmon in buildings with new copper pipes.
As they monitor the tank´s water chemistry, children will see clearly how fish affect their environment and how the environment affects the fish.
Semi-open System Disadvantages
What kind of salmon would you prefer?
Selecting a Species of Salmon
In Washington State, most schools raise either coho or chinook salmon. The kind you raise will be determined by:
- What kind of salmon are available in your area
- What kind the Department of Fish and Wildlife recommends for release into your creek
However, if both kinds are available and both may be released in your creek, you may be given a choice. Here is some information to guide your choice.
- Coho are smaller than chinook, grow more slowly, and put less strain on your tank.
- We have observed that coho are quieter and calmer than chinook.
- We have found that coho hatch well in water 46-48° F. They feed well in water about 48-50° F.
- How long can you keep them? Coho naturally spend about a year and a half in fresh water. This means you may, if you like, keep them for up to a year and a half in your aquarium. If you choose to do this, we recommend that you release all but 10 in March or early April. Release the rest in June or, if someone will care for them, you may keep about 5 or 6 over the summer and until spring of the following year. They may be up to about 3-5 inches long by then. Release them into your creek so that they can migrate to salt water on schedule.
- Chinook are larger than coho and grow faster. This will put more of a strain on your tank and you may have to be especially vigilant about keeping it clean.
- Chinook are highly alert, active, and generally "wilder" than coho. They also seem smarter, although "smart" is a relative term here!
- We have found that chinook hatch best in warmer water, about 50° F. They feed well in water about 50-52° F.
- How long can you keep them? Chinook have a shorter freshwater phase. You will probably want to release most of them in March or early April but you may, if you choose, keep about 6 in your tank until mid May. They may be up to about 3-4 inches long by then. Release them into your creek so that they can migrate to salt water on schedule.