Out of interest, are the fish in your blackwater biotope Gasteropelecus levis, P. axelrodi, and Hyphessobrycon amandae? I daren't venture a guess at the larger black and silver ones but I'm trying to learn.
There are at present 63 fish in that 29g.
Parachierodon simulans (the green or false neon) is the centrepiece with 16 but there are also four
P. axelrodi that are so closely related genetically they interact as part of the entire shoal of 20. I built the tank around the
P. simulans, as they are wild caught, an extremely delicate/sensitive species, and occurring in blackwater habitats. I don't deliberately create stained water, but with all the wood and the dried leaves added weekly the tannins and bacteria are present without the staining. The GH and KH are zero, the pH somewhere around 5. This is crucial for
P. simulans.
There are 8
Hyphessobrycon amandae you spotted, 8
Nannostomus eques (the rocket or diptailpencilfish), 4
N. unifasciatus (very close to the
N. eques, with some authors suggesting these two species might be found to form their own genus phylogenetically), my 4 remaining Loreto Tetra (
Hyphessobrycon loretoensis) that I acquired 6-7 years ago, 2
Characidium fasciatum (I think they may be male/female, I've had them for several years), five
Farlowella vitatta fry I raised from a spawning of the parents in another tank, and then the 12 hatchetfish which are species in
Carnegiella. These are the smaller of the hatchets, compared to the species in
Gasteropelecus and
Thorachocharax (I have groups of these in another tank); I have
C. marthae, the two forms of
C. strigata ("Marble"), and possibly
C. schereri which is very close to C. marthae.
The
C. marthae/schereri is perhaps a species complex, as quite recent work has identified three probably distinct lineages within
C. marthae just from specimens collected in the Rio Negro basin, that will mean three distinct species if this proves correct. This species is quite widespread, in blackwater and some clear streams throughout the Brazilian and Peruvian Amazon basins, and whenever a species has such a large distribution area, there is every liklihood it can evolve into geographical variants if the populations become isolated (as seems to have occurred with the Marble Hatchet,
C. strigata, which has two very distinct pattern forms that to my recollection have never been found living together) and these may then continue to evolve into distinct species.
All of these species do occur naturally in blackwater habitats, so they share identical water parameters, environment (sand, wood, floating plants, leaves), dimmer light, and they are all sedate. An active swimming species in this tank would be havoc and highly stressful to these fish.
I will start out with sand, roots/branches, and floating plants, and take it from there. I am a little unsure as to how easy it will be for me to source appropriate leaves yet.
Some fish stores sell dry almond leaves, but if you live near a forest or woods, or have trees in your garden that are not subjected to any pesticides or chemicals, it is easy to collect fallen leaves in the autumn and bag them up for use all year. Oak is especially good, along with beech, maple...pretty much any hardwood. Avoid evergreen leaves and they are thicker and contain more sap that can cause issues. Collect the leaves after they fall naturally off the tree, as they will be completely dead. Lay them out to dry (some people wash them, I don't, provided there are no bird droppings) for a day or so, then bag them in some old fish bags. They will float when first put in the tank, usually taking 2-3 or 4 days to waterlog and sink easily, and then they can be laid on the sand. Some fish love to "inspect" under them for food.
The chain sword,
Helanthiium bolivianum, planted in the sand was not initially intended; I had some pulled out of another tank and just stuck a few plants in to get the tank bacteria going, and it started sending out runners and I left it, though I do cut some plantlets and discard them now and then to keep it in check. I intended no lower plants because I wanted good floating, and the light is not bright to begin with, plus the Farlowella do tend to chew slowly through the leaves. Yet the plants are still spreading, so all is well. When that picture was taken in early December, this tank had been set up like this with these fish for four months. The tank was running prior to that, with the sand and some plants but much less wood.
Byron.
