Sharks – The freshwater variety
This topic of freshwater sharks is an interesting one that needs to be explained and clarified over a few times. The fish covered by this article are the “sharks” that freshwater fish hobbyists and enthusiasts around the world keep in their home fish tanks. They are generally fish ranging in size from 10cm to 35cm long and generally come from the rivers and streams of Thailand. The fish most commonly kept in aquaria are the Silver Shark, Rainbow Shark and Redtail shark.
When most people think of sharks, they think of the monstrous predators of our oceanic waters and coastlines. Whilst these fish certainly are sharks, they are actually a different category of fish than most other fish (including the freshwater sharks of this article) and are actually classified as cartilaginous (the skeleton is actually made of cartilage) fish rather than more common bony skeleton fish. That’s the first complexity to get our head around.
The next complexity is that some of these cartilaginous predatory sharks can live for many years in freshwater. The Bull Sharks can live for extended periods of time in the freshwater reaches of rivers and even in land locked lakes. There are also other river sharks that live almost all of their lives in freshwater but these generally need saltwater to breed.
So now, let’s get back to the topic – Freshwater sharks. These are a group tropical freshwater fish (with a bony skeleton) that generally live in the rivers and creeks of Thailand and northern Malaysia as well as Cambodia and Vietnam. They are freshwater fish that have their entire lifecycle in freshwater. As the Silver Shark, Redtail and Rainbow Sharks are very popular fish, they are produced in large numbers. Most of the world’s supply is bred and grown in hatcheries and farms around Bangkok, Thailand. Interestingly, the sharks need injections of hormones to make them spawn in captivity. Twenty-four hours after the injections, the large numbers of eggs are scattered and then fertilised in the tanks. The fry are then grown out in large concrete ponds and are harvested for sale in around 2 months when the fish are around 5cm long as this is the most popular size sold.
The Sharks are a popular tropical fish due to their interesting colouration and generally hardy and tolerant nature. Ideal water parameters are a neutral pH of 7 and a temperature of around 25 degrees Celsius. Most commercial fish foods are eagerly eaten by these fish.
The Redtail and Rainbow Sharks have Albino varieties that are very popular as well as the original wild colour varieties. The majestic Silver Shark grows up to around 35cm and is equally at home in a small community tank of fish or a tank with other large fish. Sharks are generally good additions to many community tanks of fish.
Guest Post: Jared Patrick, Premier Pet