Home

>

Fish

>

Food & Nutrition

>

Overfeeding Fish: Why It's a Problem and How To Avoid It

Overfeeding Fish: Why It's a Problem and How To Avoid It

Updated On November 1st, 2024

Image profile

Reviewed By Petco's Animal Care, Education and Compliance (ACE) Team

Overfeeding can contribute to loss of aquatic life. Overfeeding results in the accumulation of additional waste due to uneaten food and an increase in the amount of waste produced by the fish eating more than they really need.

Overfeeding fish is so easy to do. First, we forget how small they are: our appetites are much bigger than their stomachs! Second, feeding is one of the only ways we can interact with our aquatic life, so we tend to do it too often. Third, fish quickly learn that our approach often means food is on the way. They come to the front and top of the tank, appearing eager and hungry. Don't be tempted to think this is an indication that they are famished and need food immediately. Overfeeding is definitely too much of a good thing and can lead to serious consequences.

Problems associated with overfeeding fish

Accumulated uneaten food and fish waste pose several problems, as listed below. First, they can result in lethal changes in water chemistry. The decomposition of these products in increased levels are toxic and can stress aquatic life, making them prone to other diseases. Overeating itself can cause health problems. Finally, the pond or aquarium can become very unsightly from an increase in algae growth.

·       High ammonia and nitrites - The protein in uneaten food and fish waste is broken down into ammonia and nitrites, which are extremely toxic to aquatic life.

·       Low oxygen levels - When organic material (uneaten food and fish waste) decays, it is an aerobic process, meaning it uses oxygen and produces carbon dioxide. This means there is less dissolved oxygen in the tank or pond for  aquatic life.

·       Low pH levels - Just as the breakdown of organic material lowers the oxygen level, it also lowers the pH of the water because acids are produced during the process. Since each species of aquatic life has an optimal pH range, those species that prefer an alkaline environment are especially stressed.

·       Fin rot - Fin rot is a condition in which the fins can develop a torn, shaggy appearance. It most often occurs when fish are stressed, which can result from overfeeding.

·       Fatty liver - Fatty liver, or hepatic lipidosis, is a disease more commonly seen in African cichlids and rainbowfish and is the result of overeating. It affects the function of the liver and can result in death of the fish.

·       Improper digestion - In ponds, the amount and type of food must be changed as the weather becomes colder. Below 60°F, you should feed wheat-germ-based food exclusively to your koi, and since bacterial digestive processes will gradually slow, the amount fed should be decreased. Below 50°F, the bacteria in a fish's digestive system are no longer able to process food and you should stop feeding altogether.

·       Algae bloom - Algae growth is one of the most common problems seen in ponds and aquariums.  One of the leading causes is overfeeding. Unsightly blue-green and red bacteria multiply when there are large quantities of dissolved organic material, nitrates, and phosphates in the water, common occurrences when aquatic life is overfed.

·       Cloudy water - Cloudy water in either a pond or aquarium can be caused by decaying organic matter. If due to overfeeding, the water will generally clear if the aquatic life is not fed for 2-3 days (for most fish this is not a problem).

·       Mold - If the gravel, plants, and other décor have white, cottony material growing on them, the problem may be mold or fungus. As with algae, these organisms grow when there are increased levels of organic material in the water.

·       Planaria (flatworms) - Planaria are small white or tan worms that are good indicators that water quality is not optimal. They are most often found in tanks where overfeeding has occurred. Although generally considered harmless, they will eat fish eggs and can harm young shrimp species.

·       Clogged filters - Filter systems are designed to remove the normal amount of waste materials and breakdown products from the water, not correct the excessive problems that occur with overfeeding. Uneaten food and waste materials can collect within the filter, continue to produce toxic products, and reduce filtration thereby reducing their capacity to function effectively.

How to avoid overfeeding fish

The first step to avoiding overfeeding is to understand how easy it is to do, and how harmful it can be. This will give us the motivation to develop good habits when it comes to feeding our aquatic life. Try to incorporate the following tips to prevent overfeeding:

·       Feed on a schedule - Most tank inhabitants will do well if fed twice daily. If possible, more frequent and smaller feedings are preferred. In nature, most fish do not eat large "meals" like we do but are foraging and "nibbling" throughout the day.

·       Feed the proper amount - The best way to determine how much to feed your fish is to observe them at periodic intervals while they feed. Add small amounts of food at a time . If all the food has been eaten within several minutes, feed a small amount more. The general rule of thumb is to only feed them as much as they can eat within 1-2 minutes. Anything not eaten after 2 minutes will likely never be eaten. As you observe your fish eating, check that all of them are eating. Some fish will eat within seconds, others, such as the scavengers, take more time. Not eating may be a sign of illness or due to more aggressive or larger fish prohibiting other fish from eating.

A common error is to feed according to tank size - adding more food to a larger tank, even if it has the same or fewer inhabitants as a smaller tank. Always feed based on the number of inhabitants, not the size of the tank. Regardless of the tank’s size, spread the food out over the surface of the water to allow more fish to eat at the same time.

·       Feed the proper food - Feeding an improper, poor quality, or stale food will not only lead to malnutrition, but it will also lead to more waste, since the aquatic life will not eat it. Choose the appropriate form (e.g., flake, pellet, frozen or freeze-dried) and the appropriate size based on the tank or pond inhabitants. Some fish will need floating food, while others prefer food that sinks. Research the feeding habits of your species, and feed accordingly. Be sure to use fresh, quality foods.

If switching to a new food, feed sparingly to start. Fish may take time to identify the new diet as food.

·       Remove uneaten food - If there is uneaten food left after a feeding, remove as much of it as possible with a siphon or fine net. Regardless of the size of your filtration unit, it was not designed to correct all the problems associated with overfeeding.

If you know or suspect overfeeding has occurred, perform a partial water change by siphoning 25% of the water from the bottom of the tank. Use the siphon to pick up and remove as much debris from the substrate as possible.

·       Include scavenging inhabitants - Scavenger species like, catfish, loaches and invertebrates can assist in eliminating some of the uneaten food that falls to the bottom of the tank or pond. They are not a "fix-all" but can be helpful in removing food that falls to inaccessible areas of the tank that may be difficult to siphon or clean.

·       Educate family members and "fish-sitters" - In general, it is best if only one family member feeds the fish. If such a schedule is not possible, use a simple log or calendar to mark off when the fish have been fed to avoid duplicate feedings.

When leaving on vacation, you have several options:

·       Use a vacation or automatic feeder that your "fish-sitter" can check on.

·       If you will only be gone 2-3 days, most fish will not have a problem if they are not fed during that period. Be sure they have been fed well for the week or so prior to leaving.

·       If you have herbivorous species, add a live plant, such as Anacharis to the tank. Many fish will nibble on the plant when other food is not available.

·       If you are going to hire someone to care for your fish, try to find someone with experience. Contact your local aquarium or pond society for possible contacts. Review the feeding instructions with them carefully, and pre-measure individual portions for them.

Use proper filtration - When designing your aquarium or pond, be sure to size your filtration units correctly. Conduct routine maintenance on your filtration system to ensure it is operating at peak efficiency.

Vote icon

271Pet Parents found this article helpful

Related Questions

I have a cat that as a kitten was very ill. We got him from 7 months old. We knew he’d had cat flu prior to him coming here. He is now nearly 5 yrs old. He picks huge fights with our other cat. He keeps urinating and scratching at doors and windows around the house. We allow him to go out via the cat flap unlimited. What is happening to him

I'm glad to see that Pippin has been neutered because this eliminates that possibility of hormone-fueled behavioral changes and aggression. Behavioral changes in cats can occur at any point in time, and could be related to anxiety or stressful situations (even rearranging furniture or introducing new people to the home can be stressful to cats). Without a lot more information and observing Pippin's behaviors, I can't precisely tell you why these changes are occurring. It may be best to consult a veterinary behaviorist in your home so that they can observe everything firsthand. You can also try using calming pheromone collars or diffusers (Feliway is one example), and discussing the use of anxiety medication with Pippin's vet. I hope that all goes well!

Read More

Hi! My cat was recently diagnosed with diabetes. He’s taking insulin and taking antibiotics for a Uti. It’s been 4 weeks and he wobles when he’s walking. He can’t jump up on the bed like he used to.He’s blood sugar is 250 it’s better than it used to. I don’t understand why he’s so wobbly.

Cats can develop what's called diabetic neuropathy, where their hindlegs become progressively weak. The best thing to do is try to get his diabetes under control as quickly as possible. Here is a link describing the conditon: http://www.diabeticcatcare.com/DCCCOK/Neuropathy.htm

Read More

My senior cat has metastized cancer.17 yrs old. My vet gave her predizone1 and one half tabs a day.i wanted to know if i can just stop the meds.

Is there a reason you want to stop the prednisone? I would recommend not stopping it and if you feel it is better to stop the prednisone then I would recommend weaning off of the prednisone. I would discuss how to wean the prednisone with your veterinarian. Thank you for using Boop by Petco.

Read More

My dog has an ear infection

Sorry to hear Marley isn't doing so well with his ears. It is not possible to tell from tge picture tve exact nature of the irritation but if it is indeed infected (typically red, hot, painful and smelly), he will need prescription medication from his regular vet. In the meantime I recommend gently cleaning tge outer war with cotton wool and a pet safe ear cleaner to reduce the build up of wax/discharge

Read More

My dog vomited a pinkish colour. Does this look like blood vomit? She doesn’t have diarrhoea or anything else. Yesterday i fed her plain chicken with rice.

That is very red vomit, however, this color could be linked to a number of things including blood in the vomit, inflammation of the GI tract, having chewed on a toy this color, eaten a food item this color, or gotten into a plant or other item this color. If the vomiting continues, worsens, or other symptoms appear such as a painful or bloated abdomen, diarrhea or blood in the stool, or severe distress, I would schedule a veterinary appointment right away to rule out more severe issues. In the meantime I would continue the bland diet for 24 hours, and monitor for any additional vomiting or illness symptoms.

Read More

My dog developed a red hairless bloody mass on her skull overnight. I don’t think she bumped her head on anything.

Poor Marley! Unfortunately there are a number of possible reasons for these raised nodules and a picture cannot diagnose the underlying cause. Itis not possible to distinguish between a wound from a bug bite, cyst, benign histiocytoma or even a tumour without a physical exam and possible testing by an aspirate taken by a needle during the exam or even removal and biopsy. I recommend you follow up with your regular vet, especially if it increases in size, is painful or persists.

Read More

image

Have a Vet Question?

Book an appointment with the pros – our expert vets are here to help.

Book Now

Filed Under

Sponsored