From watching an experienced aquarist feed their fish, you might be forgiven for thinking that this is a relatively inexact science, however the reality is that fish feeding should be a scheduled and relatively precise portion of your aquarium or pond keeping regime, and here are a few reasons why:
Choosing the right fish food
This is the first thing you need to think about. Take a look at the fish in your tank or pond and research what find of food they require. Are the omnivorous like most fish? Or do they have more specific dietary needs? For example, the clownfish in Swell UK’s own 500L tank feeds on a mix of plant and animal matter served up in the form of fish flakes, however our Marine Betta (aka, ‘Jaws’) would in the wild enjoy a natural diet of small crustaceans, so once we have fed the other fish, Jaws gets his own portion of brine shrimp based food.
Generally speaking, the lesser of two evils when it comes to fish feeding is to under-feed. It might leave them a little hungry, but the effects over overfeeding can be much worse as we will find out later.
For most fish, feeding should take place only once daily, and you should allow your fish to simply eat as much as they can within 2-3 minutes. Make sure you remove any uneaten food at the end of the feeding session using an aquarium net or pond net, as not doing so is probably the biggest mistake aquarists make when it comes to fish feeding:
The Dangers of Overfeeding
Overfeeding your fish is one of the worst things you can do. Other than the obvious problem of your fishes’ health suffering from being overweight, uneaten food can seriously affect your water quality.
Your fish’s food is made from organic matter and contains proteins and other nutrients required by your fish, but this also means that it can decay, entering the nitrogen cycle of your fish tank/pond.
This means that uneaten food that has sunk to the bottom, mixing with your substrate releases ammonia as it begins to break down. Ammonia is poisonous to your fish, inhibiting their ability to breathe and high concentrations can cause an alkaline burn on your fish’s scales, similar to being burnt with acid! The process of breaking down also uses up vital oxygen in your water that would be better served allowing your fish to respire.
The beneficial bacteria in your filter, live rock and substrate may be capable of dealing with a normal amount of ammonia in your pond or tank, but the sheer amount of protein being broken down into ammonia caused by overfeeding is more than likely going to be too much for your existing cultures. Even worse, the nitrogen cycle is such that the ammonia has to first be changed into Nitrites – even more poisonous to your fish – before it can then be changed into relatively harmless Nitrates.
The increase of ammonia in your water has other indirect effects too: by entering the nitrogen cycle, it acts as a fertiliser to the algae in your pond or tank, often causing large blooms to form that are unsightly, but even worse than that – they take away even more oxygen from the water, causing your fish to suffer more problems, even death.
Other problems include a plunging pH level and mould growth around uneaten food that can quickly spread around your tank creating problems of its own.
Fish Feeding Best Practice
As we mentioned, it is best to under-feed slightly than overfeed in any way. Let your fish pig-out for 2-3 minutes and remove any uneaten food before it has a chance to sink and effect your water quality, then reduce the amount of food you put into the water in the first place to avoid wastage.