The Cardinal Tetra
If you were to ask someone what their favourite fish is for a tropical aquarium or even name a fish for a tropical fish tank, the Cardinal Tetra is usually the fish that springs to mind, and not without good reason! A well planted tank with a shoal of adult Cardinals looks amazing. Any fish tank, be it a large five foot aquarium or a small 30 litre heated bowl, a group of Cardinals will usually be the focal point. I thought I would give a brief summary of one of the most popular fish in the aquatics hobby.
The Cardinal Tetra (Paracheirodon Axelrodi) is found naturally in South America in the upper Orinoco and Negro rivers. These rivers are naturally more acidic and have a lower mineral content and are often referred to as "black water rivers". This water chemistry is almost the polar opposite to the water chemistry found in the majority of people's mains water and possibly where people run into problems.
Some aquarium shops stock wild caught specimens and there is a huge industry based around the farming of these fish within the Amazon basin. Thousands of people are employed to catch and farm these fish in a sustainable environment, contributing to the economy. However these fish are not used to the water chemistry we have here and the change can cause problems.
To help Cardinals adjust even more you can gradually add some of your aquarium water to the bag as they are floating in your tank. A small amount every 10 minutes over a 30 minute period is enough. Ideally they would be kept in softer more acidic water (you can buy various buffers and additives to achieve this) and if you wanted to breed them this is essential as Cardinals are very difficult to breed in the home aquarium as their natural habitat needs to be mimicked really closely.
There is also a debate as to whether Cardinals are a suitable fish for a newly set up aquarium. I know a lot of people say they should only be put in a fully mature system, but really any fish would prefer going in a fully cycled aquarium! As long as the aquarium is being stocked slowly, the feeding is done carefully and the water quality monitored (which should be done with any aquarium anyway!), and you make sure the fish are used to hard more alkaline water I think that they can be added relatively early to the stocking period.
Cardinal Tetras are a shoaling fish so the more you have the better - at least 4 but I would recommend 8 or more. They love a well planted tank with tall plants to create shaded areas. Try and avoid bright lighting if possible. They will accept a variety of foods including flakes and small pellets but really benefit from live or frozen daphnia. They are a peaceful community fish and get along with pretty much everything and can have a life span of up to 5 years.
Cardinals really are a stunning fish to keep and will brighten up any aquarium. It's easy to see why they are amongst the top, if not the top fish for a community aquarium.