Can we feed pond food to our trops?

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Bob Mehen gives his advice to reader who is wondering whether it's safe to feed their tropical fish with pond pellets.

Q) We have a couple of 700 l/156 gal community tanks and also a modest goldfish pond in our garden.

The community tanks include Silver sharks, Silver dollars, rainbows, gouramis, Clown loaches, Angels and a Black ghost knife fish.

We feed a dry breakfast consisting of flake, cichlid pellets, algae wafers and occasional greens; supper is usually a mix of defrosted frozen foods such as prawns, bloodworm and tropical mix.

We buy our dry food in large bulk tubs because it is cheaper this way, but what we don’t understand is the difference in price between top branded tropical flake (about £10/100g) and pond fish pellets (£0.75/100g), when according to their labels the constituents are pretty much identical. Can we safely feed our tropical fish with pond pellets?

KEN & HEV POWLEY, VIA EMAIL

A) BOB MEHEN SAYS: Feeding a wide variety a dried, frozen and fresh foods is the best way of promoting good health and growth, and it certainly appears that you are doing just this with the excellent range you use.

When it comes to dried foods then the difference in price between pond and aquarium products is notable. It’s the same for water treatments such as dechlorinators where pond versions are often cheaper, sometimes simply due to the bulk in which you can buy them.

With fish foods there are usually some noteworthy differences that may account for the apparent price disparity.

Pondfish, such as goldfish and Koi, are more herbivorous than many of their tropical counterparts and foods typically reflect this, especially in terms of crude protein with figures hovering around 25% protein for pond food but closer to 45% protein in tropical food.

Similarly fat levels in tropical foods can be almost double compared to pond feeds. Most protein in fish food is derived from fish and crustaceans (although there is an increasing trend for insect based foods) which are generally more expensive than vegetable based sources.

It’s also worth remembering that pond foods are aimed at species that live inwater where temperature changes over the year, affecting their metabolism.

Tropical species in aquaria typically exist at a set temperature with little or no fluctuation.

While you are unlikely to harm your tropical fish by feeding them pond foods, if you were to do so exclusively you may not be providing them with the best possible diet for growth and health. It should be fine, however to feed them small amounts as part of the mixed and varied diet you already provide.