You will need:

1lb (say 500g) of frozen shell-on prawns (cheapest from fishmonger or fish counter of supermarket). Mussels may also be used (no shells!).

1lb (500g) green vegetables. (I use half frozen green peas, half frozen spinach)

1 to 1.5 (570-860ml) pints water (I use water from fish tanks rather than tap water)

About 100g powdered Agar Agar (from Health Food shop)

10 - 20g spirulina powder (Health Food shop again)

5-10 drops liquid vitamins for children (I use 'Abidec' brand from chemist)


Large Saucepan
Large Plastic measuring jug
A liquidiser or meat mincer
a couple of spoons, one wooden
Lots of ice cube trays
Plastic food boxes (freezer-proof)

NB: ANY FORM OF SOAP IS VERY BAD FOR FISHES - RINSE ALL UTENSILS UNDER LOTS OF CLEAN TAP WATER BEFORE USE TO ENSURE THEY ARE SOAP -FREE.

Put the whole prawns and vegetables in a large bowl or flat surface to partially defrost.

When half-thawed, either mince, or puree in the liquidiser with enough water to ensure the prawns are chopped into the smallest pieces possible. Pour into the plastic jug.

In a LARGE saucepan, mix the rest of the water (use more than the stated amount if needed) with the agar agar. Bring to a boil over a medium heat, stirring CONSTANTLY with a wooden spoon.

It is most important to ensure you leave no thick lumps of agar agar at the bottom of the pan.

As the mixture begins to boil, remove from the heat. The agar agar will not set if it has not been boiled.

Add the prawn and vegetable mix in small amounts, stirring the mixture in the pan vigorously (you can use an electric food mixer for this). If the mixture thickens too much, return it carefully to the heat while stirring constantly.

When all the prawns and vegetables are mixed in, add the spirulina powder and vitamins drops. If you want a higher protein mix, you can add some dried fish food at this stage, adding more water if needed.

I have added whitebait but found it a bit messy, making excess waste in the water.

Finally, and as quickly as you can, pour the mixture into the jug and then into the ice cube trays, filling each compartment fully. Alternatively, the mixture can be set in flat sheets, which can be easily broken into suitable sized pieces when frozen.

Allow to set and cool before putting in the freezer at its coldest setting. When totally frozen, it can be put into plastic food boxes in the freezer until use.


When feeding, break the blocks up in to pieces to suit the size of the particular fish you are feeding with a knife or your fingers.

If you find any hard lumps of agar agar in the food, do not feed them to your fishes.

The mixture can be pressed through a sieve if you are feeding it to fry or very small fishes.


FOOTNOTE: I have EXTREMELY RARELY had a problem with a smaller fishes choking on a piece of prawn shell - use a sieve!