8 Fish Feeding Mistakes Everyone Makes (And How To Avoid Them)

Alison Page

Alison Page


Common Fish Feeding Mistakes

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Regardless of the species, providing your fish with a balanced diet is essential for keeping your pets healthy and thriving. But fish feeding has many potential pitfalls that you must avoid, as getting it wrong often leads to health problems for your fish and even fatalities in extreme cases.

I have over 40 years of experience in the hobby, but I did make a few elementary fish-feeding mistakes when I began my journey as an aquarist back in the day!

So, I’ve written this article to help you avoid making the fish-feeding mistakes I did and a few more besides. Keep reading to ensure you feed your fish in the right way from day one!

Key Takeaways

  • High-quality, protein-rich diets tailored to specific fish species are critical for preventing nutritional deficiencies and promoting vibrant health.
  • Be mindful of food portions and suitability; feeding mistakes like incorrect food size or type can cause health issues and water quality problems.
  • Implement smart feeding practices: store food properly, maintain a consistent feeding routine with a fasting day, and manage tank capacity to avoid stress and waste buildup.

Now, here are some of the most common fish-feeding mistakes everyone makes and, more importantly, how to avoid them!

Nutritionally Poor Diet

Imagine if you were fed nothing but junk food; you wouldn’t thrive, and you’d look terrible! Well, it’s the same for your fish.

A fish’s diet should generally be high in protein. Growing fry and juvenile fish should receive a diet containing at least 50% crude protein. As the fish age, their growth rate decreases, so the protein levels in the diet can be reduced. Then, protein levels in the diet can be between 25% and 40% crude protein.

Cheaper fish food tends to be packed with fillers and grain with little or no nutritional value. So, look for foods primarily containing fish meal or whole fish products. In addition, the essential amino acids contained in fish meal are essential for fish health.

High-quality fish food contains crustacean by-products, whose carotenoid pigments are great for enhancing your fish’s colors. Finally, essential vitamins and minerals are often added to good-quality fish food but are lacking in the cheaper brands.

Incorrect Food Size

Feeding to many koi fish by hand in the fish big ponds

It’s essential to feed your fish the correct size of fish food.

For example, betta fish have tiny, upturned mouths, and if you offer your fishy friend large flake food or oversized pellets, he won’t be able to eat or digest them properly. That could lead to your fish not getting enough to eat and uneaten food polluting the tank water. You’ll also be wasting money!

If you feed your fish frozen meaty proteins, that’s an excellent choice. But you must remember to break the food into smaller pieces so that every tank resident gets their fair share of the spoils.

Feeding the Wrong Kind of Food

You wouldn’t buy your vegan friend a hamburger, would you? Well, don’t offer your carnivorous fish a diet more suited to a herbivore!

To be fair, there are so many different brands and types of fish food to choose from, all promising to provide your fish with a balanced, highly nutritious diet; it’s almost impossible to pick one.

Before buying fish food, research each species you keep thoroughly to determine whether your pets are omnivores, carnivores, or herbivores. Then you can choose a suitable fish food for them. Remember that you might need to buy more than one food to keep everyone happy.

Poor Food Storage

Feeding Baby Bettas in the Aquarium with Frozen Baby Brine Shrimp

Since dry fish foods typically contain relatively high levels of fish meal and or fish oils, they tend to go off quickly. Also, ascorbic acid or vitamin C is critical for most fish species’ healthy growth and development since they can’t synthesize it themselves. Unfortunately, it’s also highly volatile.

Consequently, you should buy your fish fresh, dry food at least once a month, ideally more frequently. Store the food in a cool, dry place, and never keep it for over three months. I don’t recommend keeping your dry fish food in the fridge because of the high moisture content in that environment. That said, you can usually freeze-dried foods safely to extend their shelf life.

Overfeeding Your Fish

Overfeeding your fish is probably the most common fish-feeding mistake newbies make in the hobby.

Many fish species, such as bettas and goldfish, are notoriously greedy and will simply keep on eating until the food is gone. Overeating leads to health problems, including bloating, constipation, and, subsequently, swim bladder issues.

Uneaten food ends up in the substrate, where it decomposes, polluting the water and potentially causing ammonia and nitrate spikes, which are deadly to fish.

I recommend feeding your fish little and often, replicating most species’ eating habits in the wild environment. So, feeding your pets when you get up in the morning and again at teatime is fine.
If you’re not around at those times, investing in an automatic fish feeder is a good idea to do the job for you.

Ideally, you should offer your fish only what they will eat in a few minutes. If there’s any food left uneaten, you’re probably overfeeding your fish.

That said, fish are opportunistic feeders in the wild, gobbling up whatever they find immediately, simply because they don’t know where their next meal is coming from. Captive fish, especially wild-caught ones, are hard-wired to overeat, so it’s up to you to properly manage your pets’ diet.

Not Fasting Your Fish

Although it might sound cruel, having one day per week when you don’t feed your fish at all is a great idea. Most fish species digest their food quite slowly, meaning that if you feed them too often, a backlog of undigested food accumulates in the fish’s gut, potentially causing health problems.

Not feeding your fish for 24 hours allows undigested food to pass through the fish’s gut before adding more. If you think about it, fish are opportunistic feeders in the wild, grabbing food items whenever they find them. So, wild fish most likely don’t eat every day.

Feeding at the Wrong Time of Day

Woman feeding beautiful goldfishes at home, closeup

The most popular aquarium fish species are diurnal, meaning they are most active from dawn to dusk. The best time to feed these fish is in the morning when you get up and again at dinner.

Other fish, like some catfish and plecos, are nocturnal, coming out of hiding after dark to eat. The best time to feed these fish is just before you turn off your tank lights for the night and right before you turn the lights on again in the morning. If you want to see your nocturnal fish, try using a moonlighting setting on your light unit.

Overcrowding Your Fish Tank

When you feed your fish, they generate waste. Your biofilter deals with that waste, processing ammonia into nitrites and less harmful nitrates. You can keep nitrates at safe levels in the water by carrying out weekly partial water changes and maintaining your filtration system properly.

However, if you overcrowd your aquarium, the filter system will not cope with the amount of waste the fish produce, and the environment will quickly become toxic.

Of course, the simplest way to avoid the problem is not to buy too many fish in the first place. The specimens for sale in your local fish store are usually juveniles with growing to do. So, that tiny two-inch Comet goldfish you fell in love with and bought home could quickly expand to reach over a foot long!

Remember that many fish species, such as bettas, are highly territorial and will become extremely aggressive and stressed if kept in an overcrowded tank.

When stocking your fish tank, carefully check the species’ full size and find out how many of each type you can keep in your aquarium to avoid overcrowding.

Final Thoughts

Feeding your fish correctly is crucial for their health, correct growth, and overall well-being. Don’t make the fish-feeding mistakes we’ve highlighted in this article!

  • Avoid overcrowding your tank
  • Feed your fish a high-quality diet
  • Feed your fish at the correct time to fit the species
  • Don’t overfeed your fish
  • Store food correctly
  • Offer your fish the correct size of food to suit them
  • Include one fasting day per week
  • Feed your fish the correct kind of food

If you feed your fish correctly, they should thrive, grow, and live a long, happy life.

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