Triops: Ancient Wonders

Author: Colin Dunlop

Bring a piece of the prehistoric home with triops, peculiar creatures with an otherworldly visage and remarkable biology.

Surely I can’t be the only one who fell for the deceptive advertising campaign? I can vividly remember being a wee boy staring at an ad in a comic book showing what had to be the coolest pet animals ever—they were pink monkey mermaid people with big, happy faces. There were even mommy and daddy monkey mermaids cuddling their two monkey mermaid kids. The ad had bold captions, such as “own a bowl-full of happiness” and “millions thrilled beyond words.” Who could resist buying them?

My Experience

I was just like the plethora of other children, and their respective parents, who didn’t read or understand the minute disclaimer, “Caricatures shown are not intended to depict Artemia.” The hatched-out creatures turned out to be nothing more than cleverly advertised brine shrimp; it was certainly disappointing to say the least.

To us aquarists brine shrimp are seen as nothing more than fish food, and I now realize that since the days of seeing the ad in the comic book, I have single-handedly sent untold millions of these monkey mermaids to an early meeting with their monkey mermaid maker.

What does all of this have to do with my topic? Well, I was given my first batch of triops as an unwanted second-hand Christmas present from a relative who decided she had no need for them. I was handed a gaudily colored box covered in happy, smiley shrimp things emblazoned with bold text claiming that I could “hatch out my own prehistoric monsters.” Does this sound like a familiar claim?

Hatching a Project

Needless to say, as an adult who was once stung by a similar gimmick, I was fairly dubious, and the box was unceremoniously dumped into a cupboard for a few months. I can’t remember what spurred me on, but I eventually decided to try and hatch them out (perhaps I ran out of live food?). I therefore dutifully followed the instructions for hatching my own “prehistoric monsters” and set up my first-ever triops kit complete with small plastic tub that came with the box. (I must admit that the tacky replica volcano never got its feet wet!)

Since that first hatching a couple of years have gone by, and, unlike with that childhood disappointment, I was hooked and have since gone on to keep and breed several species of triops. I still can’t believe that I had never heard of these amazing animals before. If you can see past the gimmicky way that triops are often sold, I recommend that you give them a try.

Triops Biology

Triops look similar to trilobites or perhaps even horseshoe crabs at first glance, but they are actually shrimps from the Branchiopoda group. This means that they are closely related to a few other animals we often associate with aquariums, such as daphnia and, of course, artemia. The reason they are labeled as being prehistoric or living fossils is because their earliest records go back some 350 million years to the Paleozoic Era’s Carboniferous period. The European triops Triops cancriformis has remained unchanged all this time, and it is regarded as being the oldest living species on Earth.

Triple Vision

The name “triops” is translated as meaning “three eyes,” and this is because they have two compound eyes and one naupliar eye. This third naupliar eye is very similar to the eyes of many crustaceans’ first larval stage and is only capable of differentiating between light and dark. Most other nauplii lose this eye during their development, but triops retain it.

(Almost) Instant Food

As fishkeepers, there is a good chance that some, if not most of us, have used Artemia nauplii as a source of food for young fish. You should therefore be familiar with the state of suspended animation, also called diapause, which the eggs of brine shrimp are able to achieve. This is partly why Artemia is such a popular and convenient food, as the eggs can be harvested, dried out, and stored for long periods of time until they are needed and ultimately hatched out within 24 to 48 hours under the right conditions to be an on-demand food.

Long Life

Triops have a similar capability, but the diapause stage of their lifecycle can last more than 30 years! Unlike Artemia, the triops eggs do not need any salt in the water, and distilled, spring, or rainwater seem to bring a higher hatching success rate than tap water.

Hatching Triops

Triops live in ephemeral pools, which mean that they are, at best, living in seasonal water bodies that may only contain water once every few years, and even then only for a few weeks at a time. These generally inhospitable habitats require some pretty extreme survival strategies, which triops utilize in several ways to ensure that the next generation can pick up where their parents left off.

Egg resilience

Starting with the eggs themselves, which is how many are normally introduced to these animals, it is notable that they have a remarkable resilience. Not only can they survive freezing temperatures, extreme heat, and desiccation, but they can also pass right through the gut of another animal or blow about in the wind for years and still hatch out when the conditions are right. The ideal conditions for egg hatching would be for them to have wound up in a pool of water that will last a couple of months. These temporary pools are unsuitable for fish species, so predation from fish is virtually non-existent. Their natural lifespan is somewhere in the region of 50 days depending on species.

Hatching Process

Triops eggs will not all hatch simultaneously. This is a safety mechanism that prevents hatching in a pool that dries up in a day or two and kills all hatched triops. Another strategy they have to prevent unsuitable hatching is that they require not only the presence of water, but it has to be water of specific parameters. And as if all this wasn’t enough, they are able to detect light and dark conditions, so if an egg is buried in mud, the egg won’t hatch until it receives light.

In our hands, the eggs have a comparatively easy time because they can be hatched out in any dedicated aquarium with a few centimeters of water. Room temperature is okay for some species, though a few will require tropical conditions, so check the requirements of your triops accordingly. I normally use a small, air-operated sponge internal filter for some filtration, and I initially don’t add any substrate because the eggs will normally come in a small bag of coral sand.

Finding the eggs in the sand is not easy, but once the water is added you may see them at the surface of the container against the sides. The coral sand will help buffer the pH, and a neutral value seems to suit most of the species. To begin, just pour the sand and eggs into the tank and add either deionized, distilled, or RO water with a 75/25 mix with tap water. The reason that pure water is used initially is to convince the eggs that it is a brand-new water body with no build up of dissolved organic compounds, as that would suggest a resident population of predators.


You should be able to see your first few hatchlings within a day or two, and quite often a big batch will hatch on days three through five. Do not feed the triops for the first few days, as they are living off their yolk sac. They are about the same size as newly hatched brine shrimp once hatched, and I often add a couple of water snails to help eat uneaten food.

Some species are more prone to cannibalizing their younger siblings than others, so you might want a separate tank for the first ones to hatch. You can very slowly increase the water level with tap water by a few centimeters each day once the triops have hatched out. I have lost whole colonies by undertaking water changes, so I suggest that you never change more than 10 percent at a time. Also make sure that new water is left to sit for at least 24 hours before use.

Raising Triops

You will not believe how quickly these animals can grow. They can literally double in size every 24 hours—starting at a miniscule ½ mm, they become nearly fully grown within the first couple of weeks from hatching. Really, it all happens that fast! Some of the larger species such as T. cancriformis grow slower than others, but they can still reach their average 5- to 8-cm (2- to 3-inch) lengths in just a few weeks.


First foods will be found by the newly hatched triops, which are usually microscopic particles that came in with the same bag of sand that the eggs arrived in. You can start feeding them extra from about day three onward. They only require very small amounts of food, so little and often is the ideal way to feed them. Powdered fish foods are fine, and I have had a good success rate with crushed-up cichlid pellets and other sinking granules.

A Simple Strategy

Part of the long-term success of triops is that they grow faster than anything else in their ponds or pools, and then eat everything else! Unfortunately, that also means that you might wind up with just one or two large triops.


Larger triops simply require larger food items and, as they are omnivorous, will appreciate some fresh food in their diet: peas, carrots, grindal worms, and most other foods that are fed to fish. They can also eat their shed skins that are cast off during their growth spurts, so I tend to leave them in the aquariums. But if the triops are well fed, the skins just float messily around, so you can remove them if you want.


My eventual goal with any of the animals I keep is to try and encourage them to breed. I have bred some tricky species over the years, but if you are looking for your next challenge, this isn’t it. In most cases you don’t even need two triops, as they can breed parthenogenetically—asexual reproduction. Many other species are hermaphroditic.

They can start to reproduce after only about two to three weeks of age, and although some eggs may hatch in the aquarium, the vast majority will not hatch unless you remove the substrate and dry it, essentially starting the whole process of the lifecycle again. They can be quite easy to breed and secure future hatchings.

Great for New Hobbyists

In closing, I would recommend keeping triops at least once. I was pleasantly surprised and intrigued by their lifecycle, their speed of growth, and of course their survival strategies. They would be an ideal species for getting your kids into the hobby, especially if you go for one of the kits with the fancy colors and ornaments. So forget monkey mermaids; feed those to your fish, but give a loving home to your very own prehistoric triops monsters!

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