Can Fish Die from Overfeeding

Can Fish Die from Overfeeding?

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Having an aquarium is a perfect opportunity to teach children about taking care of living things with a brief chemistry lesson. But, children love to feed fish, sometimes a little too much. It’s not unusual to find mountains of fish flakes in an aquarium because a child thought it was a good idea.

So, when you bring home your new aquatic friends, it’s important to understand that fish can die from overfeeding. In fact, overfeeding is so easy that it’s the most common reason why fish die. The resulting accumulated water waste will fast become a fatal and toxic aquatic environment.

Can fish die from overfeeding?

When it comes to eating, humans and fish are different. They have much smaller and delicate digestive systems too. Plus, since feeding is the primary way of interacting with fish, we tend to give them too much food far too often.

Also, fish are shysters. Even though they just ate, they’ll act like they’re starving. This is due to how fast they learn that a human coming toward the tank, means food is on the way. And, since most humans are sentimental suckers for their pets, they’ll cave.  Don’t do this, it can and will lead to the fish’s ultimate demise.

Problems with Overfeeding

It’s not only the risk of death that overfeeding causes for fish, although it’s a big one. When uneaten food stays too long in the tank, it can change water parameters to unlivable levels. This can also cause the fish to die due to contracting various health problems like viruses and diseases.

The dirtiness accumulated in the tank makes the environment uninhabitable and unsightly. If you have a fish that’s sensitive to water changes, this may spell out its doom. The following is a list of things that can happen all because someone overfed:

  • Algae:  One of the most common problems with overfeeding is the abundance of algae growth. Blue-green and red algae multiply in the presence of undissolved phosphates, nitrates and other organic material.
  • Clogged Filters:  If you have a large tank, chances are, you have a filter. This removes normal levels of waste while helping breakdown water contaminants. But, they don’t correct overfeeding issues and clogging will occur.
  • Cloudy Water:  When you see cloudy water, it’s a sign of decaying organic materials. But, there’s good news with this! It should clear in two to three days so long as no one adds more food.
  • Fatty Liver:  Rainbowfish and African Cichlids can succumb to a disease called Fatty Liver, or Hepatic Lipidosis. This only happens as a result of overfeeding. It impairs the fish’s liver function, often ending in death.
  • Fin Rot: If your fish’s fins develop a shaggy-like moth-eaten appearance, they likely have Fin Rot from the stress of overeating.
  • High Nitrates; Ammonia:  Fish waste and uneaten food breakdown into nitrates and ammonia that are incredibly poisonous to fish.
  • Improper Digestion: If you overfeed your fish too often, it can cause the bacteria in their digestive system to stop processing food altogether. They can die from this.
  • Low Oxygen Levels:  Organic matter decaying in a tank uses up available oxygen and then produces carbon dioxide. Less oxygen in the environment makes it difficult for fish.
  • Low pH Levels:  Just as with oxygen, pH levels will also shift in fatal ways because of organic decaying matter. Of all the parameters appropriate to fish, pH is the one that must stay the same.
  • Mold; Mildew:  Mold is present when you see a cotton-white substance growing on the substrate, plant life and decorations. As with algae growth, these can grow to dangerous levels for fish.
  • Planaria:  Also known as Flatworms, these are small white or brownish creepy crawly things. This indicates poor water parameters due to overfeeding. Flatworms are not particularly dangerous, but they will feast on fish eggs.

What is the right amount of food for fish to eat? 

A few flakes two times per day are sufficient for most fish. As a general rule, you should only feed fish what they can consume in two minutes or less. Also, several small meals throughout the day are much better than one large feeding. If there’s food left over, remove what you can with a net and feed them less next time.

How can you avoid overfeeding fish?

It is imperative all caretaking household members understand how easy and harmful overfeeding is for fish. So, you want to develop good habits to ensure your fish lives for as long as possible.

Therefore, it might be a good idea to create a fish feeding schedule. For the first few days, feed with everyone in the household together. Then, you can break down the schedule and allocate who should feed the fish at what time. Create a calendar and have everyone mark down what day and time the fish received food.

Additional Tips

  • Although most fish are fine with two times per day, more is better with tiny amounts. If more than three people are going to do be feeding fish, then create a schedule. This will be better for the fish in the long run too.
  • Also, during these first few feeding events, monitor how much fish eat in two minutes. Start small, like three flakes per fish, and then increase or decrease as needed. Whatever you do, don’t feed according to tank size; always feed based on how many fish you have.
  • When you feed, spread the flakes over the water’s surface so more fish can eat at the same time. When it comes to feeding, some fish are going to be more aggressive than others. Thus, you want to control bullying as much as possible.
  • Food quality is also a crucial factor. If you give improper, stale or poor food, not only will it result in malnutrition but it can create more toxicity issues. Research what’s best for your fishes and how they like to eat it. Some like pellets and others like flakes; some like to eat it mid-water and others like to eat at the water’s surface.
  • When switching food, do this sparingly and mix it with some of the previous food because some fish take a little time to identify a new diet.  Remove any uneaten vittles as soon as possible.
  • Another good idea is to get a clean-up crew for your tank. They are a great help with uneaten food. Things like loaches, catfish and some invertebrates can help prevent contamination.
  • In case overfeeding happens, perform a partial water change from the bottom of the tank. Use a siphon to remove 25% of the debris from the substrate.


It’s terribly easy to overfeed fish and it’s important that all caretakers understand this very poignant aspect. So many health issues can arise that cause fish to suffer and die; something you want to avoid happening at all costs.

Therefore, you want to make sure you take the necessary steps to avoid doing this. Pay attention to the appearance of the water, check the tank for plentitudes of uneaten food and take care of any issues the moment you see them. Being meticulous will keep fish healthy, happy and thriving.

See Also:
Why Does Algae Grow in Fish Tanks
Can Fish Tanks be in Direct Sunlight
How to Sterilize Fish Tank after Fish Died