South American Tetras
This is the largest group of characins encountered by aquarists, and includes all the wellknown species such as Paracheirodon innesi (Neon tetra), Hasemania nana (Silver-tip tetra), Hemigrammus erythrozonus (Glowlight tetra), Paracheirodon axelrodi (Cardinal tetra), Hemigrammus bleheri (Rummy-nose tetra, Rednose tetra), Hemigrammus rhodostomus (also known as the Rednose tetra, or Worm-nosed tetra), Hyphessobrycon erythrostigma (Bleeding Heart tetra), Nematobrycon palmeri (Emperor tetra), Moenkhausia pittieri (Diamond tetra, Pittier’s tetra); and so the list goes on.
The South American tetras are, in the main, small fishes which are well suited to life in the community aquarium. They require soft, slightly acid conditions such as usually prevail in a mature furnished aquarium. Many people fail with them because they are too eager to add Paracheirodon innesi (Neon tetra) is commercially produced by the thousand for the aquatic trade so there is little fear of decimating wild stocks. them to a new set-up. The tank needs to have been in operation for several months before adding even the more hardy species such as H. eryihrozona. Six months to a year’s maturation is best for the more delicate species such as cardinals. They are shoaling fishes, which like the company of their own kind, so rather than buying one or two of this species, one of that, and two or three each of several others, purchase eight or ten of your favourite and maybe six or eight of another. By doing this you will see more of the fishes, as given company they will not hide away in the plants.
Feeding is very simple. They will take commercial flake foods as a basic diet, but, in order to maintain some of the hues on the body, it is essential to feed either live or frozen foods. By varying the diet you will also be able to get the fishes into breeding condition should you wish to attempt to spawn them.
Of the small tetras, neons have the reputation of being horrend-ously difficult to breed, and yet the truth is they can be spawned with almost the same ease as many of the barbs. The key to success lies in your choice of potential breeding stock and in how you set up the breeding aquarium.
In healthy well-fed fishes sexing is quite easy. Females tend to be larger and generally more rounded than males. As they fill up with roe this will become even more noticeable. The blue longitudinal stripe will also appear curved on the female, but straighter in the male. It may be a little difficult to see this difference, but body shape should be enough to separate the sexes without too many problems.
Take care in selecting the correct sizes of neon tetras to try to spawn. Big is not beautiful in this case. You need to look for fishes which are just over half grown. The 2-3 cm range seems best. If you only have a choice between extra large or very small fishes then take a group of small ones and grow them up. It is better to wait a few months than to try to breed fishes which are too old and will never spawn for you.
In preparation for the spawning attempt you need to condition your potential breeders with plenty of live foods, such as Daphnia and newly hatched brine shrimp. It is also important to lower the pH and hardness of the water in which your fishes are living, to prevent them from going into shock when they are transferred to the breeding tank; over the few weeks it will take to condition your breeders with live food you should therefore slowly add rain water or demineralized water to the tank to soften the water and lower the pH.
The breeding tank is now ready for its intended occupants, which are best introduced in the evening, just before “lights out”. Hopefully the next morning you should see your pair embracing off and on for a couple of hours. During these embraces the female turns to an almost vertical position with the male wrapped around her. Each time a few eggs are expelled and since they are only semi-adhesive some of them may fall through the nylon mops and drop to the bottom of the aquarium. During a good spawning up to 150 eggs may be laid. As soon as the pair have finished mating they should be removed to another aquarium (with matching water chemistry).
Sometimes a pair will not be ready to spawn as soon as you place them in the breeding tank. In this case leave them for a few days to see if they will spawn. If, after this time, they have still not bred, then remove them and try another pair, or wait for a week and try with the originals again. Under no circumstances should you risk pollution by feeding the adults in the breeding aquarium.
Once the adults have been removed cover the tank with dark brown paper to exclude some of the light. The next day the eggs should hatch; and on the fourth day after spawning the fry will become free-swimming and will need to be fed the very smallest of foods such as infusoria or a liquid fry food, followed after a week or so by newly hatched brine shrimp. Once feeding on brine shrimp, the fry grow quickly and will be sexable after about 12 weeks.