I've had 4 Guppy fishes with big red tails which called 'Red Apple'.   They were active and friendly (They swam to the front screen when people got close to the aquarium). Every time I brought MeiTau to watch the fishes, the guppies swam to the front screen and MeiTau purred with joy. Then they looked like communicating!  After a period of time, the Guppies died one by one until the last one was very sick and hid alone in the inner corner. Well, I could only brought MeiTau to say last goodbye to it... As soon as MeiTau appeared in front of the aquarium, the Guppy swam to the front screen. Instead of her usual purring, MeiTau kept silent. They 'talked' for a while until I brought MeiTau away. The Guppy swam back to the corner and was found dead in the next day. I still wonder if they can communicate. If you know, please tell me.