Signs Of Underfed Fish And How Much To Feed Them

Feeding is the daily job of fish owners. However, it may not be as easy as you imagine, and you will make the mistake of feeding your pet too little.

We will discuss some signs of underfed fish. Observing them lets you know if you are treating your pet correctly. Then, take immediate action to save its life.

Let’s follow our post and learn to be a caring owner!

Signs Of Underfed Fish

How do you tell if you are underfeeding your fish? You need to check for the following signs for the answer.

Weird behaviors

Your fish might be searching for food if you see it swimming in areas where it doesn’t often visit. The hungry fish may dig in the substrate to feed itself.

Both scavenging behavior and fish examining the top of the aquarium are behaviors it wouldn’t usually engage in. But now you see them, and they are signs of hunger.

Change in appearance

Some fish owners wonder, what does an underfed goldfish look like? You can only find the answer by looking closer at your pet.

Underfeeding may cause your fish to become smaller than it should be for its species, both in terms of weight and size.

Aggressive attitude

When you feed your pet, if it acts aggressively and eats quickly afterward, you can be certain that it is starving.

Fish eat fast, but if you see your fish working extremely hard to eat as much food as possible in a short period, it probably has been too hungry.

goldfish in aquarium

Your fish will behave differently when they are so hungry

Is It Better To Underfeed Fish?

Compared to overfeeding, you will see that underfeeding is still better because:

  • You will waste a lot of expensive food if your pet can’t consume all of it.
  • Overfeeding has the potential to pollute water, which can result in animal death or require costly remedies.
  • Your fish will only become somewhat more active due to underfeeding as they will be more alert to people surrounding the tank.

Although underfeeding poses fewer threats to your pet and tank than overfeeding does, improper feeding, in general, affects them severely.

How Long Can Fish Go Without Being Fed?

There is no one-size-fits-all answer to this question because fish are available in different varieties, and each has specific feeding requirements.

This chart will show how long some species can live without food:

Species How long they can live unfed
Bettas 1-2 weeks
Goldfish 10 days
Koi 2 weeks
Guppies 7-10 days
Tetras 10 days
Platies 10-14 days
Mollies 2 weeks
Angelfish 1 week
Plecos 10-14 days
Oscars 2 weeks
Barbs 2 weeks
Gouramis 2 weeks
Loaches 10 days
Swordtail fish            2 weeks
Corydoras catfish       2 weeks

Besides, you can determine how long to leave your pet without food based on:

  • Age: Adult healthy fish can live for one or two weeks without food. Meanwhile, young fish cannot survive for a long time without food because they lack the fat reserves of adult fish.
  • Size: Larger fish will fare better without feeding than smaller fish.
  • Feeding behavior: Herbivores require daily feeding. Hence, they will suffer more from underfeeding than carnivores that only eat every few days.

Although fish have a higher tolerance than you may expect, we do not recommend starving your pets for too long. This experience is risky, and you may lose your lovely friend because of underfeeding.

How Do I Know How Much To Feed My Fish?

You can establish a perfect feeding plan for your pet after considering things:

How active is your fish?

How much to feed your pet depends considerably on its metabolism. Since smaller fish are more active, they require more food than bigger, slower fish.

Tetras and rasboras are two examples of small, young predators that are frequently active. Part of what makes them so charming is the way they rush around, nibbling at one another and discovering their habitat.

These fish would naturally feed continuously as insect larvae, plankton, and other food occasionally floated past.

In aquariums, they have a sizable feeding all at once that satisfies them for a few hours. So, you need to feed these animals twice, maybe even three times, a day.

Your fish will have a faster metabolism in a warm environment. However, many tropical fish, like danios and minnows, may thrive in cooler water.

You should either feed the tropical species less frequently or at fewer feedings in cooler aquariums (one to two times per day). Any further and you’ll either see fat fish or wasted food.

group of neon tetras

Some fish are active and eat more than others

How big is your fish?

Body mass links to metabolism closely. We can conclude that the metabolisms of bigger fish are slower than those of smaller fish.

It’s a trade-off because larger fish require more food to support their body weight than smaller fish do.

Larger fish can generally stay longer between feeds. Adult Goldfish, which have slower metabolisms, should only eat once daily.

Due to their endless hunger, adult goldfish are among the easiest fish to overfeed because they don’t care how much they eat earlier. When they get older, their metabolism also slows down.

Most fish can survive three days to one week without feeding before having problems, though you shouldn’t try this test.

It’s beneficial to occasionally skip one day to improve digestion and promote the burning of stored fat.

You can get the same effects by giving small fish with fast metabolisms one light feeding now and then.

You can discover more feeding tips right here:


Unfed fish will be slower in movement and smaller in size. You can also notice some weird behaviors from your hungry pet.

Giving your fish the right amount of food is not easy. However, with some research, you will find the most suitable solution.

Thank you for reading!