Tips for Choosing Fish for a Cold Water Aquarium

By: Matthew Olsen

Tips for Choosing Fish for a Cold Water Aquarium

The majority of aquarium fish that are on the market can actually be considered in an unheated tank. The problem however is that without a heater in your tank the temperature can change relatively quickly. These temperature swings send most fish into shock and can be fatal to them. The fish that can adapt to these temperature changes quickly are considered to be cold water fish because of this ability.

When beginning to look at fish to go into an unheated aquarium you need to look at a few factors that will determine the type of fish you will buy. How large a fish will get and how well it can survive in a tank with constant temperature swings are the two questions that are specific to choosing cold water fish. By answering these two questions you can easily verify how well a fish will survive.

The size of any fish determines ultimately if you can even think about putting it in your tank. For example koi are a well known cold water fish but they can grow to be as big as 24 inches long easily requiring 500 gallons per fish. Not even I know someone who has a tank that big!

Temperature swings are the kicker. How can you tell from that little two inch by four inch square in front of the fish's tank if it is the right one? Well you must keep in mind that all fish can live in an unheated aquarium. The determining factor is not there on that little info sheet provided so I have a few fish listed that can survive temperature swings fairly well.

Goldfish are not as big and being related to koi is a definite choice in a cold water tank. They are very common fish and are not at all expensive. The only problem is that they are hostile to any small fish that are not of their own type.

Barbs, tetras, and dianos are all relatively small fish growing almost three inches and can live in a cold water environment. These fish relatively like the water to be in the low sixties but can survive in lower temperatures. These fish are schooling fish and rarely can survive on their own.

Loaches are the substitute to catfish you can use in your tank to clean up after other fish. These scavengers will pick up anything that was left over after feeding time that the other fish missed. They are not all suited for this type of tank however but the two that seem to be the best are the hillstream loach and the weather loach.

Last but not least guppies and white cloud minnows are the best of the best of cold water survival besides goldfish. They can go to low temperatures and come in many different colors. These fish are also schooling fish, grow to about one or two inches, and are very easy to come by.

These fish are the best at adapting to changing temperatures but they are not the only ones. Other fish can be in an unheated tank but they must be located where the temperature does not change suddenly. With the right size of tank and correct location you can have almost any fish you could want in your aquarium.