How Do I Know If My Fish Needs More Food? (Explained)

Actually, most aquarists overfeed their fish rather than under-feeding. However, if you are underfeeding your fish, it can cause serious health issues. So, it’s better to look at the signs of underfeeding and determine if you need to feed your fish more food.

Here are the signs to know your fish need more food:

  • Fishes Look Always Hungry
  • Not Growing At a Regular Rate
  • Nibbling On Substrates, Plants & Glass
  • Getting Aggressive and Attacking Smaller FIshes
  • Always Looks Tired
  • Losing Weight
  • Color Starts Fading

In this article, I am going to discuss all the signs that you are underfeeding your fish. I will also explain how you can fix this by feeding your fish the right amount and at the right frequency. So, let’s get started!

7 Signs of Underfeeding Your Fish:

1. Fishes Look Always Hungry:

The most basic sign of underfed fish is that it will look hungry all the time. However, there are some fishes that are aggressive eaters.

You might find it difficult to understand if it’s really hungry or not. I have gold gourami and I faced such an issue with this fish.

It always looked hungry despite how much I fed it.

So, you will have to draw a fine line in between. What I did was, I fed my fish 2-3 times a day and as he was a fast eater, I gave him enough food that he could finish within 1 minute.

There is a misconception that you will need to put enough food in the tank which your fish can finish in 3 minutes.

The thing is it is correct if your fish are not too aggressive eaters. I have kept several species of fish in my fish tanks over the years. What I have seen is that, for most fishes, you will need to give them food that they can finish within a minute.

Also, some pet store owners or aquarists will tell you to feed your fish once a day, but I have found my fish grows faster and stays more active when I feed them multiple times (2-3) in small amounts.

2. Not Growing At a Regular Rate:

All the fish has its own growth rate, some fish has a faster growth rate whereas other has a slow growth rate.

if you have a betta fish that is 7 months old then this fish should be around 2.25 to 3 inches in length.

If your betta fish is shorter in length then it might have a growth rate issue due to nutrition. So, take care of your aquarium fish and offer them a proper diet to prevent the growth rate issue.

3. Nibbling On Substrates, Plants & Glass:

I’ve seen my Gold Gourami nibbling on substrates and plants as he gets hungry. Gold gourami can get quite large up to 6 inches when fully grown.

But gets about 3 inches within a few months after being born. Gold gourami requires a good amount of nutrition for its growth.

In my case, I kept my gourami with guppies and zebra danios. What I have seen is that gourami tends to get quite hungry and start nibbling on plants and substrates as if it was the larger fish in the tank.

When I was feeding all the fish in the aquarium, he almost always ate around 80% of the overall food. This indicates gourami gets quite hungry and you need to give him proper amounts of food on a regular basis.

Other fish also start to do the same when they become hungry. In the wild fish eat a variety of food including worms, smaller fish, insects, algae, leeches, etc.

However, while in the aquarium their food habit becomes pretty limited. So, having a good diet for your fish would be beneficial. 

4. Getting Aggressive and Attacking Smaller FIshes:

Most carnivorous and omnivorous fishes will become aggressive when there is a shortage of food in the tank.

If you are not giving your fish enough food, they will start attacking smaller fishes and invertebrates.

I have seen betta fish attacking Amano shrimps when it’s hungry. So, if your fish are attacking other fishes all of a sudden, then there is a big possibility that your fish need more food.

5. Always Looks Tired:

Your fish can get tired more easily if you are underfeeding them for quite some time. They will start to swim slowly and get weak in the process.

You will know your fish is tired when you see them have less control over buoyancy, sitting on the tank floor, staying still in a particular position, sometimes even floating upside down.

Due to the lack of nutrition and proper diet, fish get weak and tired, and they can also get stressed when they are tired.

As you might know, stressed fish can easily catch the disease. From my experience, I used to feed my fish once a day on a daily basis, my fish gets a little bit aggressive while eating the food.

Then I learned that you need to feed them two to three times a day with a small amount that the fish can finish within one minute.

6. The belly is Sinking Inside:

This is another sign that your fish are not getting enough food and nutrition. If you are underfeeding your fish, then the belly of the fish will get sunken inside.

On the other hand, overfeeding will make your fish obese. So, feed your fish the right amount and if you see that your fish is slowly losing weight and its belly is sinking inside, try to increase the amount of food gradually.

But don’t start overfeeding.

7. Color Starts Fading:

Many people, including have experienced color fading in aquarium fishes. This can happen for a lot of reasons. But starving is one of the main causes.

If you constantly underfeed your fish, it will start losing its color. I noticed that a long time ago, in my goldfish.

But once you start feeding the right food in the right amounts, the color becomes brighter again in no time.

So, if you notice that your fish’s color is becoming faded or pale, that is an indicator that, it’s not getting enough food and nutrition.

Bad Effects of underfeeding fish:

  • Growth Slows Down
  • Weight Loss
  • Fish Will Always be Stressed
  • Fish Immunity Will be compromised
  • Will not Live Longer
  • Losing Energy & Interest in Mating
  • Becoming Unsocial
  • Turning Pale

Related Questions:

Why Do My Fish Act Like They Are Starving?

Most fishes are opportunistic eaters. In nature, they don’t get to eat all the time so they keep looking for food all the time.

That’s why it is very common for fish to keep looking for food and pretend to be hungry all the time in the fish tank, even though they are fed well.

Can Fish Die From Overfeeding?

Overfeeding a fish can cause a lot of issues such as increasing bioload, ammonia, nitrogen and which can ultimately kill your fish.

There are also other negative effects of overfeeding such as producing more poop, disrupting the digestive system, and poisoning the aquarium water.

Here is the list of effect that can cause by overfeeding your fish:

  • Fish will produce more waste
  • Fish waste will damage the water parameter.
  • There will be issues with the fish digestive system.
  • Excess leftover food will poison the water, increasing the ammonia, it can also turn into Nitrogen and poison the fish.

Final Thoughts:

There you go! I have pointed out all the signs that could mean your fishes are underfed and need more food.

I have been keeping fish for a long time now. I noticed these signs in my fish and I had to figure out everything on my own.

From what I have seen most of the time, I had issues with overfeeding. Underfeeding issues only occur when you mix regular and aggressive eater fishes in the same tank.

As I told you, I kept guppies and danios with gourami. Gourami used to eat all the food and other fishes were starving. When I figured it out, I started feeding them separately in the same tank.

You can also do it by spreading foods all over the tank, by not putting all the foods in one place.

Asif Iqbal

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