I’ve been thinking about fish, and what a brilliant resource they are for educating and entertaining children. I’ve come up with a few activities you might want to try with your child.

Go to the fish counter of your local supermarket. You’re looking for things like herring, trout, sea bass. Go at the end of the day. Try to get them when they’ve been reduced. Buy the ones you like the look of – ideally get a couple in different sizes. I like herring and trout best.
Open up a black bin liner, cover your table or part of a hard floor, and examine your catch.
Some people are squeamish about touching raw fish. Children usually aren’t and at some point your child will poke its eyes out. All good. It’s scientific discovery. They’ll like the teeth too. Fish have surprisingly sharp teeth. Children love to put their fingers in fishes’ mouths. They’ll probably make them talk to you too. Your hands will smell; of course they will but “discovering” together that rubbing lemon on your hands gets rid of the smell is all part of the science fun.
Painting fish is relatively mess-free. Take a brush and literally paint all over the fish, make sure you paint the head/tail thoroughly. Too much paint and the scale pattern will disappear. Carefully lie a piece of paper on top, carefully shape it round the fish and gently rub. You will get a beautiful scale print and a fish outline. Children love doing this. It’s nice to do it with different-sized fish. Your child is having a great time and incidentally learning about – size, printing, descriptive words, colour, imaginative play, sharing.
Two small fish in a bowl of water can be swirled round to make them swim. See how fast you can make the water swirl. Did you use a finger, a spoon, or something else?
“Two little goldfish swimming in a tank. One called Freddie and one called Frank. Swim away Freddie, swim away Frank. COME BACK FREDDIE, COME BACK FRANK!” This makes children giggle. They nearly always recognise it as a variation on “Two little dickie birds.”

Paper plate fish are easy to make. Get some paper plated in different sizes. Cut a triangle out of each one (maths again). Stick the triangle on the fish’s bum to make a tail. If the plate’s big enough, add fins and teeth. You don’t need me to tell you how to decorate a fish but, for my sake, put a bit of glitter on.
What are you going to do with the fish when they’re done? Well, after they’re dry, they can go on a sea collage or be made into a mobile with a bit of string and two sticks. Or…you can make an aquarium. Easy, I promise. Take a cardboard box, cut a big oblong out of one of the big sides. This is best done by the adult with a Stanley knife. Thread your fish on bits of string and stick to the inside of the box lid. I prefer masking tape – it’s easier for children to use. When you close the box, the fish “swim” in your aquarium. You might want to decorate it or make other sea creatures/plants. Go and watch Spongebob if you’re stuck for ideas.

Children’s paints are non-toxic but I wouldn’t eat a fish that had been played with and I wouldn’t recommend you do but, if you do, please wash the paint off and cook it thoroughly first.
What I would like, however, is a fish finger sandwich. It’s maths again. Fish fingers are oblongs.. How many do you need? How do we fit them onto the bread? What if we change the shape of the bread? How do we make the fish fingers fit? This is wonderful maths problem-solving and logical thinking. (No sauce on mine please)
Finally, a nice fishy read.
There are so many lovely fishy books that I’m going to link you to Amazon’s fish book page. Choose your own. They’ll all be available from the library too. http://www.amazon.co.uk/s/ref=nb_sb_noss?url=node%3D69&field-keywords=fish
Any book that has Usborne in the title is a good one, and I’m very keen on “The Fish who could Wish.”
I Googled webcam aquariums and found this. There will be others but this is lovely http://www.montereybayaquarium.org/efc/otter.aspx?c=ln
All of these activities can be done outside if you’d prefer. I think you’ll be amazed at how much general knowledge your child already has about fish life – thank you, Nemo.