Thank you for the information. I like the green tetras.... unfortunately I have less now. I recounted theres 4... not sure if I can get more I only saw them at big Al's and I'm a bit angry with them. Will they school with neons or cardinals?
Yes, but with cardinals rather than neons. Phylogenetic analysis shows that the cardinal
Parachierodon axelrodi and the green tetra
P. simulans are very closely related, differing in their DNA by only a couple of chromosomes. The neon tetra,
P. innesi, is a more distant relation.
This very close genetic relationship means that conditions favouring one species will generally favour the other. Both
P. axelrodi and
P. simulans are found in identical habitat environments...very soft and acidic water, warmer temperatures, often blackwater. They are sympatric species (meaning, they occur in the same watercourse together) in some of their habitats but not in others. Both species are associated with flooded areas of the Negro river basin;
P. axelrodi inhabits waters that do not exceed 30°C, and
P. simulans lives at temperatures that can surpass 35°C (D.F. Campos,
et al, 2017). The neon
P. innesi is not found in such environments but in much cooler clearwater streams and does not occur sympatrically with either of the afore-mentioned species.
So the cardinal and green neons will always consider each other "family" so to speak, more than the neon. And your aquascape can suit them equally well. I acquired my previous group of
P. simulans some years ago, and as my older group of
P. axelrodi began dying off, I moved the remaining three or four in with the
P. simulans, and they were inseparable.