I have a relatively new aquarium (35l, planted aquarium, 2 1/2 months old, 20% water change once a week).
In mid February we introduced 5 pygmy cories (not sure of sex, think 3 females and 2 males), and they were fantastic. Swimming all over the tank, playing together, and vacuuming the tank bottom.
After three weeks (three weeks ago) they'd settled in nicely and everything had stabilised so we introduced six immature endlers livebearers (3 male, 3 female). At first they all got on fine, even playing together, but now the cories have gone really quiet and shy, so much so that they barely move anymore
The endlers seem fine and are very lively. The cories all look OK, still got their barbels, one maybe has slightly faded coloration but that could be my imagination. They do still swim about and feed but spend 99% of the time sitting on the gravel at the back of the tank. This is worrying because they had been so happy and lively.
What are the possible options?
- are they intimidated by the endlers?
- are the endlers outcompeting the cories for food? (but they don't go after food when it's dropped right next to them in the tank)
- are they depressed - we have hidey holes and plants, but is that not enough? Do they need counselling?