Next time you buy frozen food for your dear pets, keep your eyes open. There might be a surprise waiting around the corner, or rather, in the ice, as shown by our “quality check”.


For this test, we bought two types of plankton that had been kept in the refrigerator of an animal feed seller. All the tablets of both types of the plankton that we were examining looked identical, there were no visible differences. From outside, the packaging looked attractive and it was professionally made. Each “container” in the blister pack housed a frozen cube of plankton, of whitish transparent colour, and on the bottom of every single container there was a layer of easily identifiable deposited fine granules.


On one packet it said “Red Plankton”. On the other “Green Plankton”.

The colour of the layer on the bottom corresponded to the writing on the label. But if the bottom layer was the plankton, then what was the ice cube? Was there something else other than water and some lime scale precipitate? The aquarists who have frequently used these “ice cubes” for introducing food in their aquariums, expecting them to feed their wonderful corals with precious plankton, have made a very simple mistake, without knowing it. Instead of food, they introduced almost only water.

The ice cube dissolves in the water of the aquarium, and with it the “Corpus delicti”. A more accurate exam of what remained after defrosting it has revealed that there was some plankton in it, but at an incredibly low concentration. The drained weight of the plankton could not be expressed as a percentage anymore, instead we had to use a permillage.

Calling such a product “frozen food” requires much creativity and humour.


Those who think that these products are completely useless are very wrong. After all, they are always useful to the producer. It must be said that these watery tablets of frozen food, which contain almost no food, have a great advantage for the aquarist. should the cold chain be interrupted, for example if the tablets were to heat up and defrost while taking them home, there would be no need to worry about their contents deteriorating. All kidding aside, this example shows very clearly that you should not blindly trust the products you buy, especially if you occasionally change type and producer.

The majority of the producers of frozen food definitely offer quality products, there is no doubt about that. It should also be said that the producer of the food that we have examined here should not necessarily be considered a fraud, but at least their carelessness should be pointed out. Anyway, the possible fluctuations in quantity are huge. Therefore we recommend that you always check the label, even if it is just simple frozen food.