Freshwater Fish

An overview of freshwater fish breeds

Freshwater fish must, by definition, live in water with salinity levels below 0.5 percent. Physiologically speaking, both domestic and tropical freshwater fish have extremely well-developed kidneys, which help them process the large volumes of water they take in. In the wild, freshwater fish that lose too many gills will become sick and die because they will absorb too much water in their blood and internal organs.

Some fish species can go back and forth between salt water and fresh water, spending most of their time in one while going to the other to breed. Salmon and trout are common examples, though some other familiar species like eels also perform this switch.

Exotic freshwater fish such as betta fish, while popular with aquarium hobbyists, need to be kept in highly controlled conditions. In some cases, these fish cannot tolerate a water temperature that deviates more than a few degrees Fahrenheit from optimal levels, or their health will suffer. Thus, it's important to take the time to learn proper maintenance of freshwater fish tanks before you purchase any fish.

Freshwater fish aquariums require reliable pumps and filters to ensure toxins don't build up in the water. As a general rule of thumb, you should change at least 10 to 15 percent of the volume of water in your tank each week, even when water cleanliness is aided by aquarium pumps and filters. The professionals at your local aquarium store can tell you more about the ideal living conditions for the type of freshwater fish you choose to buy, including proper pH levels for the water and acceptable temperature ranges.

Algaefix for freshwater fish tanks keeps the growth of algae in check, which also helps keep living conditions in the tank optimal. It's crucial to maintain a delicate balance when it comes to algae. Some species, including catfish and koi fish, like to graze on live algae; even so, too much algae contaminates the water, so be careful if you include rocks with live algae growth in your aquarium. As an alternative, you can feed algae wafers to your fish, so they can satisfy their cravings without you worrying about conditions in the tank becoming dangerous.

The prices of freshwater fish for sale vary according to the vendor and the relative rarity (or commonness) of the species. Simple goldfish cost very little, while strikingly beautiful and specially bred koi fish may command hundreds of dollars each. Set a budget and stay within it, keeping in mind that it'll cost you between $50 and $100 for a good aquarium and at least $10 to $20 a month for fish food.