signs of overfeeding fish

10 Signs You Are Overfeeding Your Fish

Signs of overfeeding fish

Feeding our aquarium fish is one of the most fun activities of aquarium keeping.
Feeding time provides personal interaction between the aquarist and fish and brings the fish up close so we can see them.


It’s one of the best times to see their colors and scale patterns and check on their health.
Many fish seem to recognize their caretakers and will come to take a closer look when you approach the tank and you may even be able to enjoy hand feeding your fish.
There are no discussions that proper nutrition keeps aquarium fish colorful, healthy and disease-free.
No matter the reason feeding is important and fun.
But the fact is, feeding should be done cautiously as overfeeding causes nothing but problems in the aquarium.
The question here is:

how do you know you are overfeeding your fish and not just giving them the right amount of food they need?

Proper feeding aquarium fish is a blend of art and science.
But luckily there are signs that can tell you if you are giving too much food to your fish.
Keep reading to find out what these signs are and what you can do about it.

1. My fish are always hungry

Many freshwater tropical fish and goldfish will come to the front of the tank and “beg” for food.
This is a learned behavior and does not mean they are hungry.
Remember, fish are built to scavenge or prey on foods in the wild.
They have to find it and capture their food.
In nature fish search for tiny crustaceans, algae, and even other fish to eat.
Aquarium fish have food added daily.
Fish soon learn that your presence at the aquarium means food.
Their instinct is to eat, eat and eat.
Aquarium fish eat by simultaneously opening their mouth and closing their gills.
This creates a suction, helping the fish pack food into its mouth.
Don’t be fooled into think they’re hungry just because they’re snapping at the water surface.

2. Adding “extra” food for later

Some aquarists, worried their beloved fish will be hungry later, add more food than the fish can consume at one feeding.
They believe the extra food will serve as a snack later in the day.
If this is your concern, you can use an automatic fish feeder that will schedule the time of release of the food in the tank.
The truth is, fish food left in the aquarium will quickly soften and fall apart in the water.
Floating pellets may hold together but their nutrition is leaking into the water.
Invisible microbes immediately start decomposing uneaten fish foods.
The reason the food disappears is primarily due to decomposition, not consumption by the fish.
This leads into the next symptom of over-feeding.

3. Food on the bottom of the tank

Whenever you see flake food resting on the bottom of the aquarium and no fish are eating it, you know you’ve feed too much.
If flakes are not consumed within a minute or two, chances are they will just soften and decay on the bottom of the tank.
Over time the flakes will form a rotting sludge layer in the gravel.
Once the flakes get soggy, fish tend to ignore them.
One exception is feeding bottom feeders like corydoras catfish and loaches.
Bottom feeders will sometimes come to the surface for flakes.
Other times you have to moisten flakes to get them to sink to the bottom.
In this case just be sure there are no “leftovers” to decay when the fish are done feeding.
Small sinking pellets are great for target-feeding bottom-dwelling fish.

4. Pellets floating on surface

Some floating pellets are highly compressed.
They float for hours on the water surface.
But there should never be any uneaten pellets drifting around the tank.
If there are, it means the fish are done feeding and aren’t interested in food or they’ve over-eaten and can’t force any more food into their mouth.
Uneaten food will usually decay and fall apart in the water. The pellets are “gone” but they weren’t eaten by the fish.
This leads some aquarists to believe their fish enjoyed the extra food.

5. Dirty gravel

All aquariums eventually need a good gravel cleaning.
Organic debris like algae cells and partially decomposed fish waste will accumulate over time.
Over-feeding accelerates the process, leading to dangerous conditions that can harm the fish.
Rotting food will consume oxygen fish need to live.
Beneficial bacteria that normally live on the surface of the gravel get overtaken by more aggressive bacteria that thrive in sludgy conditions.
Some of these “sludge-loving” microbes are responsible for fish disease problems.
Disease-causing microbes thrive in dirty aquariums.
Much of the “dirt” in aquariums is caused by over-feeding.
The more you feed fish, the more solid waste they produce.
Solid waste normally gets broken down and recycled.
But when you shovel food into the fish, they become “poop machines” that convert all the extra food they can’t use into solid fecal material.
This builds up in the gravel and causes water quality and fish health issues.

6. Cloudy water

Hazy, cloudy water is almost always caused by a bloom of bacteria in the water.
Even though the bacteria are harmless, something triggered them into an explosive growth mode.
Uneaten fish food feeds the bacteria!
The sense food and eat.
This gives the bacteria energy to reproduce. Many bacteria reproduce every few hours. Eventually the water becomes cloudy due to millions of bacteria in a feeding and breeding frenzy.
Reduce feeding and the water will clear.

7. pH low

The decomposition of organic waste, like uneaten fish food, produces acids.
These acids neutralize some of the pH stabilizing carbonates (KH) in the water.
Low pH is sometimes caused by over-feeding when the carbonate hardness is naturally low to begin with.
Be sure to test KH when you experience a low pH problem.
Low pH can suppress the biological filter and lead to harmful ammonia levels.
Here are some suggestions on how to raise the pH in the aquarium.

8. Ammonia problems

As fish consume and digest protein-rich foods, they excrete ammonia from their gills.
Ammonia build-up in the water damages the gills, stresses fish and leads to disease problems.
Over-feeding the fish beyond what they need to live a healthy life results in higher ammonia loading in the tank.
You can over-feed the fish and over-feed the biological filter’s ability to rapidly remove ammonia.
Chronic over-feeding will cause a surge in ammonia.

9. Nitrite problems

Ammonia is converted to nitrite and then nitrate, by the biological filter.
Nitrite is very toxic to fish.
Over-feeding can cause high ammonia and nitrite levels or just high nitrite.
As nitrite prevents the fish’s blood from carrying oxygen, this stresses the fish and can lead to death or increased susceptibility to disease.
Test for ammonia and nitrite as part of your maintenance plan.

10. Fat fish

Healthy aquarium fish are normally slender and streamlined, making it easy to swim through the water with little resistance.
Some hybrid tropical fish and goldfish have been bred to have rounded bodies.
No matter what kind of fish you keep, it’s possible to feed so much the fish become obese.
Excess fat builds up inside their body and presses on their organs. Feeding fish so much food their bodies bloat up at each feeding will cause digestive problems.
In nature, most aquarium fish graze on food throughout the day.
They eat tiny amounts of food at a time.
In the aquarium it is sufficient to feed small amounts several times a day, even once will satisfy most fish’s nutritional requirements.
There is no need to keep feeding the fish until they physically can’t swallow any more food.

Final thoughts

We all like to feed our fish.
It’s rewarding to see our fish respond to us and eat the food we provide.
Our fish look to us for their food and care.
Over-feeding degrades water quality, creating stressful conditions that lead to disease and possibly death.
Fish will always act like they are hungry.
Over-feeding can reduce their quality of life by forcing their body to build up fat deposits.
If you enjoy feeding your fish as much as we do, feed smaller amounts of food several times a day.
You’ll get to enjoy your fish more and they’ll stay happy and healthy!

10 Signs You Are Overfeeding Your Fish