Making your own fish food
Husbanding saltwater fish is an eye-wateringly expensive pastime, in part due to the cost of the fish food purchased from speciality shops. For the past year I have been feeding my fish with home-made food. The results have been very positive: perky, colourful fish and good growth. This article describes the recipe that I use. Notes describing my equipment and fish are at the end of the article.
Saltwater fish are, by and large, omnivores. Crudely, this means that they will try and eat pretty well anything that fits in their mouths. Thus, what follows should be taken as guidelines rather than absolute truths. My Banggai cardinal is a strict carnivore; my tangs (which the literature describes as herbivores) prefer meat to vegetables, given the choice. As an extreme example, practically all my fish will eat bananas if they’re hungry; yours may not.
As an aside, remember that the most important rule with aquariums is be patient, nothing happens in days, little in weeks, gentle progress in months.
I've tried to ease things by taking photos at each stage. Click on a photo to see the full-sized image.
You'll need a flexible fish paring knife and a plastic chopping board. One of those curved choppers make things much easier:
Our end result will be single-meal-sized frozen cubes of food. Ice-making trays will work but the ultimate is bakers’ moulds, which you can find at professional suppliers. They are made of flexible rubber which apparently can stand temperatures from those of Venus to those of Pluto and are a joy to use:
Not unlike food for us humans, there are two ingredients to fish food, meat and vegetables. A well-stocked fishmonger can provide you with both, with less luck you can fall back on your grocer for the latter.
Go to your local fishmonger and buy about 200g each of about 5 shellfish and 5 ‘fish’. The actual species are unimportant, it’s the variety we’re after. Here’s what I bought last time:
- Cockles (don’t bother with the small varieties,
too much work to shell them)
For the fish, I buy just the fillets (less work), pretty well all species are acceptable except perhaps bony and/or freshwater species (trout, pike, ...). *All* shellfish work wonders, feel free to throw in oysters and scallops if your budget permits. Here’s what the my catch looks like:
Notice that head of garlic top right, we’ll be dousing everything we do in garlic purée later.
Fish like seaweed, just like humans. For us, seaweed is usually sold covered in coarse salt. Our fish are already in salt water, so rinse the seaweed copiously in a sieve with luke-warm tap water until there is no froth left:
If your fishmonger doesn’t sell seaweed, no problem, use a selection of vegetables. Suitable candidates are carrots, leeks, cabbage, anything firm. Avoid potatoes (just starch), tomatoes (just water), cauliflour (falls to bits) and anything with hard fibres. Remember, your fish will only eat lumps they can see, anything that falls apart is just filter-pollution.
Put the mussels in a pyrex dish and microwave them 1 minute at 600W. The aim is not to cook them, just make them easier to open. The clams and vongole will need 2 minutes to ease them open:
Get an oyster knife like the one shown, it’ll make your life a lot easier (don’t use the version with a sharp, pointed tip, you’ll end up in hospital). Shell all the shellfish, remembering that the easiest way to crack them open is by prying the knife from the hinge side. Be careful to include the muscle in your pickings (shown with red arrows) ...
... they’re the most nutritious bits.
Slice the fish flesh as finely as you can:
dice the flesh into 1-2mm pieces:
don’t worry about the evenness of your mixture, different fish have different sized mouths, your Lionfish’s morsel is your clownfish’s gob-stopper. Continue chopping at 90° to your previous cut until you have a fine mince:
You may get the bright idea of slinging the whole mess into a food processor and pressing the button. Resist this temptation, the result will be a stringy purée which your fish will ignore and your filter will clog on.
Some fish (like tuna) have strong nerves (you can tuna piano, but you can’t tuna fish). Cut them across the grain first:
Once diced, carefully remove any stringy
bits that your fish will refuse:
Crush 10-12 cloves of garlic and incorporate them evenly in your mixture. Be generous, your fish’ll love you. There’s a bit of chopped seaweed left over in this photo, can’t do any harm:
My mould has about 1 heaped teaspoon per square. Fill each square of the mould:
Drop the mould onto the worktop several times to make the mixture settle in and smooth with the back of your paring knife:
Put the result into your deep-freeze, with turbo-freeze if you have that option, and leave for a couple of hours.
The seaweed, however, does benefit from a food processor. Toss the lot into the food processor and chop it for 1 minute. Remove the mixture and rinse it with warm tap water in a sieve until there’s no froth left. Put it back in the food processor and chop for a few minutes. Repeat until there are no obvious pieces more than 4-5mm on a side. This may well take 5-10 minutes of chopping and you’ll lose a bit at each rinse, persevere until you get something like this:
If you’ve gone the carrot+leek way, blanche them for 5 minutes in boiling water and chop them finely. Crush 4-6 cloves of garlic and blend them in with the seaweed/vegetables. Use the same process with the bakers’ moulds to make frozen cubes:
Into the deep-freeze and after a couple of hours:
You’re finished !
This is very important. Take a frozen cube and put it in a jar of warm water. Shake until it breaks up. Pour into a tea strainer and rinse copiously with warm tap water. The reasoning here is that your fish will only eat what they can see, any microscopic particles and juice are pollution for your filter (and great food for cyano
-bacteria). Introduce the contents of the tea strainer by waving it deep in the tank.
The tank and its occupants
I have a 500L tank with sump, protein skimmer, canister mechanical filter and 2 x 1200L/H powerheads:
In it I have
Royal Dottyback - Pseudochromis paccagnellae
Banggai Cardinal - Pterapogon kauderni
Yellow Longnose Butterfly - Forcipiger flavissimus
Emperor Angel - Pomacanthus imperator
Occelaris Anemonefish - Amphiprion ocellaris
Yellowtail blue Damsel - Chrysiptera parasema
Sohal Tang - Ancanthurus shoal
Blue Surgeon - Paracanthurus hepatus
Volitans Lionfish – Pterois volitans
Blue-leggged hermit - Clibanarius tricolor
Scarlet hermit - Paguristes digueti
Red-spined Star - Protoreaster lincki
Tiger Cowrie - Cypraea tigris
Snails – Astraea
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