What Do Glofish Sharks Eat? Can They Smell Blood?

Jan 7, 2022

What Do Glofish Sharks Eat

Image Credit: CCM272 (Creative Commons license)

I don’t think I have to familiarize you with a shark’s diet. Pop culture and one too many films based on these fearsome, spine-chilling marine beasts have already done that. But what about their colorful, fluorescent, and a lot more subdued miniatures that live in our home tanks? What do glofish sharks eat?

Do they also have a taste for juicy flesh? Can they, too, smell blood from hundreds of meters away? Are your other aquarium fish in danger?

Let’s find out. 

What Do Glofish Sharks Eat?

Glofish sharks are omnivores, unlike great white sharks that only consume flesh and bones. In aquariums, they eat almost anything you offer – from pellets and shrimps to algae and blanched veggies. 

As you already know, glofish sharks are made by genetically modifying rainbow sharks. And in the wild, rainbow sharks primarily snacked on algae, zooplankton, and phytoplankton. 

Therefore, besides sinking pellets, you can give glofish sharks algae in various forms like flakes, wafers, and tablets. 

And don’t forget to occasionally fortify their diet with live or frozen insects and shrimps. 

Here’s a list of food glofish sharks readily consume in an aquarium:

  • Sinking pellets 
  • Flake foods 
  • Algae flakes 
  • Algae wafers 
  • Algae tablets
  • Blanched broccoli 
  • Blanched spinach
  • Blanched zucchini 
  • Blanched cucumber 
  • Cooked and skinned peas 
  • Bloodworms 
  • Brine shrimp 
  • Mysis shrimp 
  • Daphnia 
  • Insect larvae 
  • Tubifex 

As you can see, a glofish shark’s appetite is quite drastically different from your regular sharks’. 

Any guesses why? 

Rainbow sharks aren’t actually sharks. They come from the minnow family and are actually more related to loaches and carps than actual sharks! 

I know, the elongated body, flat tummy, pointed snout, and erect fins make them look uncannily like miniature sharks. But well, they are, in fact, minnows! 

And by the way, they can’t smell blood from 100 meters away like the real sharks do. 

Do Glofish Sharks Eat Aquarium Fish? 

As mean and nasty as glofish sharks are, surprisingly, they don’t really have an appetite for aquarium fish. While we cannot 100% rule out the possibility of them eating smaller aquarium fish, it turns out that many hobbyists have successfully raised them alongside petite species like guppies and tetras. 

Are Glofish Sharks Bottom Feeders? 

Yes, glofish sharks are bottom feeders as well as bottom dwellers. Therefore, you should never keep them with other bottom-dwelling species like catfish and loaches. 

The ‘ancestors’ of glofish sharks, aka rainbow sharks, have evolved over thousands of years to feed at the bottom to take advantage of the dead organic material that eventually drifts down to the floor. 

How Often And How Much To Feed Bottom Feeders?

The rule of thumb is to feed any aquarium fish 2 meals a day. You can give your glofish sharks food they can finish within 5-6 minutes. 

With cichlids, it’s recommended to break down big meals into 3-4 small meals a day to manage their aggression over resources. 

You could try to do the same with your glofish sharks. 

Frankly, there’s no one rule set in stone to determine the feeding frequency and amount. 

I know hobbyists that fast their fish 1-2 days every week to allow them to clear their digestive tracts. And some of my friends give just one big meal every day. 

And all their fish seem perfectly healthy and happy. 

Play around and experiment until you can zero in on what’s best for your fish and convenient for you. 

How Long Can Glofish Sharks Go Without Food?

A healthy adult glofish shark can go without food for a week or two. But remember, their health will increasingly deteriorate with each passing day of starvation. 

Also, young glofish sharks can’t go without food for very long compared to adults. 

So, while your fish can be safely left without food over a long holiday weekend, you should make skipping their meals a habit. 

Recommended Readings!

How Big Do Glofish Sharks Get? Are They Even Sharks?

How Big Do Glofish Danios Get? Is Your Danio Stunted?

How Many Glofish Tetras In A 10-Gallon Tank? There’s Bad News!

What To Feed Glofish Sharks? My Recommendations! 

I have never owned glofish sharks, but I have raised rainbow sharks on and off for some years now. And since glofish and rainbow sharks have the exact dietary needs and preferences, here are a couple of my recommendations:

API Tropical Sinking Pellets 

What I Like About It:

  • Made with ingredients like shrimp pellets, seaweed, squid, and mussels for improved nutrition 
  • Stays intact for a longer duration in the water 
  • Specifically formulated for easy digestion 

Hikari USA Algae Wafers 

What I Like About It:

  • Enriched with pure cultured spirulina 
  • High in stabilized vitamin C to boost immunity 
  • Does not easily dissolve and cloud water 

Hikari Bio-Pure FD Bloodworms 

What I Like About It: 

  • Contains microencapsulated vitamins 
  • Nitrogen charging reduces oxidation before opening 
  • Does not cloud water 

What Are The Signs Of Overfeeding Glofish Sharks? 

Feeding aquarium fish is one of the highlights of my day. I’m guilty of overfeeding my fish just so they interact with me a little longer. But like everything else, overfeeding can lead to unwelcome consequences. 

Here are a few signs that you’re overfeeding your glofish sharks:

  • Leftover food remains in the tank for more than 30 minutes after feeding, and the fish shows no interest in it anymore
  • Prolific algae growth even with proper filtration and water changes 
  • Cloudy aquarium water with a foul smell 
  • Filter media becomes clogged frequently 
  • Ammonia, nitrite, and nitrate levels are spiked chronically 
  • Fuzzy or cottony white fungus at the bottom and on decors and plants 

Nutritional Deficiency In Glofish Sharks 

We’re often spoon-fed with loads of information on how we shouldn’t overfeed fish to maintain water quality. And while it’s absolutely true, we’re often unknowingly putting them at risk of malnourishment. 

Lack of vitamin C can cause broken back disease, which causes the fish’s backbone to deform.

Lack of vitamin B-complex can lead to brain, spinal cord, and nerve disorders.

Lack of protein in the diet leads to stunted growth, anemia, and decreased production.

Final Words: What Do Glofish Sharks Eat?

In the tank, glofish sharks are omnivores that accept a wide variety of food. They aren’t fussy eaters. But they’re bottom feeders. You need to get them sinking pellets. 

They also love nibbling on algae. But, the algae growing on your tank may not satiate their appetite. So, you can give them algae wafers, tablets, and flakes. 

Lastly, you can occasionally fortify their diet with frozen insects, crustaceans, and blanched veggies. 

Recommended Readings!

How Are Glofish Bettas Made? Are They Dyed Green?

How Many Glofish Danios In A 10-Gallon Tank? 5 Or None?

How Many Glofish Danios In A 5-Gallon Tank? You Might Not Like My Answer!

rohit gurung author at urbanfishkeeping

About Rohit Gurung

My never-ending love and fascination with Aquascaping started when I received a red-eared turtle for my 10th birthday.

Apart from researching and writing, I spend hours gazing at my 3 turtles. And yeah, I bask alongside them too.