AI Koi fish behaviour

I was watching 3 Koi fish in aquarium for quite long time and found out that fish behavior is not simple.I was thinking before that fish have a smallest amount of neurons, so their behavior is pretty random. But thats not true with Koi. This behavior can be used in video games or simulations. Maybe some day i will made it with unity or you can use it for any underwater creatures.

So what parameters fish have:

sex - male and female
activity - passive, active
long time memory
mood
hungry

What they can do:

- Swim slowly ( maybe random I don't figured it out )
- Swim fast
- Sleep at bottom
- Eat
- Find food
- Find food on bottom
- Male follow female with high speed

How parameters affect actions:
male follow female periodically
active male follow female, passive not
passive swim slowly most
they remember the most often place of feeding and at time of big hungry swim to that place
if they have bad mood ( was damaged ) they swim slowly most
if they are not hungry they not looking for food
Sleep when its night time
Active are much bigger

This actions can be triggered by neural network or just randomly in simplified AI model.