The reason for this evolutionary adaptation? Predation, or rather their attempt at avoiding it, as Amazonian waters are filled with literally thousands of fish species which could put Splash tetra eggs on their menu. Every year the mighty Amazon River and its tributaries flood into the rainforest, providing an abundance of space for fish to feed and breed. With it then comes abundant overhanging vegetation (or at least there used to be,) and the Splash tetra found its survival niche while at same time cementing its place in natural history books and tv documentaries.
Copella arnoldi is the Splash tetra’s correct scientific name, although it may also be sold and listed under its synonym of Copeina arnoldi. Copeina is a related genus of similarly shaped fish, as is Pyrrhulina, yet despite looking superficially similar, and mistaken for the true Splash tetra at times, only Copella arnoldi, named after ichthyologists Edward Drinker Cope and J. Paul Arnold, uses the extreme terrestrial breeding method.
Like many fish of the lower Amazon, C.arnoldi is adapted to warm, soft, acidic water, stained with tannins from the tree leaves and branches. Warm acid pools, rich in organic matter, also suffer from low oxygen levels, so laying eggs up in the air may have a second advantage – oxygen. pH can be as low as 4 and never above 7, and water temperatures can approach 30 Celsius. The Splash tetra likes archetypal Amazonian water conditions for sure, and will be seen at its best in aquariums which replicate those water parameters, and decor.
Tank set up
The male Splash tetra grows larger than the female, yet is still a small fish at just 5cm fully grown. Despite their diminutive size I prefer to see mine swimming in the upper layers of aquariums at least 90x30cm/36×12”, and would never consider them as nano fish for tiny cube tanks. Water movement should be kept at a minimum, and if you want to keep it strictly biotope correct then use leaves and wood, over a substrate of sand or soil. True aquatic plants are rare in acid pools as the dark water blocks the light and lacks nutrients. Floating plants could be an option if you crave greenery, or some Philodendron house plants growing above the water line, with their leaves and stalks draped in the water.
A modern take on the Splash tetra habitat could be a paludarium – a glass vivarium set up with water in the bottom and jungle vegetation up above. A very natural, environmentally rich tank in which to house Splash tetras, and in theory, the ideal place for them to spawn as you can control the humidity and temperature above the water line too.
Don’t be afraid to keep Splash tetras in shallow tanks like the water areas in vivariums. In nature they inhabit the upper water levels only, and my anecdotal observations are that most small surface dwelling aquarium species inhabit very shallow waters only in the wild. If they ventured out across the surface in deep, natural waters they would be picked off by predators from below.
My OCD would flare up if I mixed Splash tetras with anything other than small Amazonian catfish, cichlids and characins, although the choice there is still vast. Apistogramma, Corydoras, Banjo catfish, and the hundreds of tetra species would all make perfect Splash tetra companions. But as soon as I stray towards Splash tetras I like to mix them with other interesting small stuff. There are the Splash tetra’s cousins to consider – other Copella, Copeina and Pyrrhulina, or how about the fascinating, beautifully delicate Pencilfish, also of the family Lebiasinidae. Plenty to study there.
Hatchetfish would make ideal tank mates, and they are far too delicate for average communities. Or what about Biotoecus, or Taeniacara dwarf cichlids? Both like it super soft and warm, again needing more specialised tank mates over hussle and bussle communities.
Avoid large, boisterous tank mates. With the exception of the Banjo catfish I wouldn’t mix them with any fish with an adult size much over 5cm.
With its upturned mouth and slung back dorsal fin, the Splash tetra is a surface feeder, so feed floating foods. In the wild this would consist of tiny terrestrial insects falling onto the surface from above, tiny insects hatching at the surface from aquatic larvae, as well as the microscopic life that can be slurped from the still surface film.
In the aquarium small flakes can make up the staple diet, but get creative and offer aphids from the garden, or first instar crickets, fruit flies and spring tails from the reptile shops. They aren’t difficult fish, but offering them a jungle diet feels right, and is so easy to do these days.
Provide the above water conditions and Splash tetras will breed. My first fish bred on the glass condensation covers of the aquatic shop I worked in. Just make sure you have true Copella arnoldi (take a phone picture along with you for reference,) and ensure you purchase both males and females. The males are larger as I said, but they also have long fins, whereas the females are small, shorter bodied, and with much shorter fins.
The male entices the female over after picking an overhead, suitable site, before embracing as the two of them leap out of the water and cling to the leaf, or in my case, the glass. They lay up to 200 eggs depending on size and maturity, and the male hangs around for the next three days, splashing water up onto the eggs until the fry have hatched and dropped into the water. The female takes no part, other than the actual spawning, and once the hatched fry drop into the water the male demonstrates no parental care after that.
The fry are typically small so feed on infusoria or strained, steamed egg yolk, and if you want them to survive, move them to an isolation tank with gentle or no filtration, and regular partial water changes. If you can raise them you should find a ready market in the shops, clubs and selling pages for the adults, as they are still by no means commonly available fish.
Copeina – often Copella are referred to as Copeina, although both genera are valid
Being so adapted to jumping, and surface life, Splash tetras aren’t suitable for over filled, open topped tanks. Always fit a lid, and with luck they’ll spawn on it!
Zikamoi [CC BY 3.0 (https://creativecommons.org/licenses/by/3.0)%5D