Three Spotted Eartheaters in the wild

Three Spotted Eartheaters in the wild

Keep eartheaters and you’ll never look at detritus in the same way again!

Ivan Mikolji takes us into the underwater world of Satanoperca daemon.

There are some fish that are more common than others in the wild. Satanoperca daemon are very common in most rivers south of the Apure River in Venezuela. The locals refer to them as Horse Face or Earth Suckers. In the aquarium hobby they are known as the Three Spotted Eartheaters; they get the name from the three black spots that can be seen on the sides of their bodies, two spots are found along the mid-line of the body and one spot in the caudal peduncle. To me S. daemon are simply magnificent. They are a living example of how a fish’s morphology and behavior adapt to fill specific niches and succeed in colonizing specific aquatic areas; in their case the benthos.

Even though S. daemon are very common to see in the wild, they are very hard to photograph. Taking “daemonfabulous” images of them is hard because they are quite shy and do not get very close to you. Once you start to approach them or enter their personal space, they simply swim away. A great example would be to try to stick two magnets together on the same poles. They maintain a very specific distance of around 3 to 4 meters in circumference around you. I have tried to trick them on many occasions to try to get a good image without much success. Hiding behind aquatic plants and rocks has not been an option either because S. daemon reside in wide open sandy spaces with very short or no aquatic plants. Rocks are simply not present in their ecosystem and if they are, they are usually the size of a football field or larger which does not make them a very convenient hideout. 

Black water, green water, blue water, oh my!”

The few close up shots I have taken are by hiding behind fallen tree trunks and the other images I have simply had to take from afar. The further the fish are from the camera, the murkier the image looks. To look for S. daemon images I had to go through thousands of images in my hard drives simply because they could have been photographed in 80% or more of our expeditions. The habitats they are found in vary greatly due to their wide distribution. I have seen them living in black water, green water, blue water and clear water. It is quite strange to see so many different tones of color images when you are referring to one type of fish.

S. daemon is one of the fish that I have observed the most in the wild throughout time. This is simply because it is present in so many of the rivers we have explored. Juvenile Three Spotted Eartheaters love to fight each other. In the wild, you can often see them quarreling. They lock each other by their mouths and shake their bodies’ vigorously. Then, they swim around each other in circles flaunting their fins and protruding their opercula. It is all an exciting display to observe because they do not harm each other and when they get tired they still stay close together as a family. It seems to be more like play time than a fight for a rank or territory. Older specimens do not fight, they have very close social bonds and are extremely peaceful with each other and other fish. It is very rare to see these fish by themselves. They usually are in pairs or in small schools of up to eight individuals. These fish love sunlight. If there is a sunny spot in the river, they will stay there, sunbathing.

Substrate stew

S. daemon spend their day sifting the substrate of the river bottom. 

Q: What do you get when you cross a fish with a vacuum cleaner and a snow blower? 

A: A Satanoperca daemon, Three Spotted Eartheater. S. daemon are not found in fast moving streams or parts of streams with a strong current. This is because their food source is found in slow moving Amazon lotic ecosystems and would be washed away by strong water current. The bodies of water they inhabit have many different substrate bottoms depending on the locality but have many “ingredients” in common. Years of firsthand experience have taught me exactly what these contain and they could be easily prepared at home. The recipe would be as follows: To make a South of the Orinoco substrate stew you would need, lots of silica sand, small decomposing tree leaves and stems, algae, a splash of freshly evacuated fish material, thinly chopped (chewed works better) aquatic plants, and a dash of mud. Once you stir all of this together, let it settle and wait 48 hours at 30° Celsius before serving. To make a North of the Orinoco version just substitute 15% of the silica sand for a thick ivory or light yellow colored clay.

Gluten free menu in the wild

So do S. daemon really eat the delicious substrate stew? Not really. They feed on the small organisms that live, feed, reproduce or hide in or on the stew. You could say that S. daemons’ benthonic gluten free omnivorous menu consist of micro crustaceans, periphyton, small worms, aquatic insect larvae including coleopterous and dipterous, very small fish, and fish eggs. S. daemon do not feed on terrestrial insects that fall in the water as most other river fish do. This is due to their morphology. Their specialized subterminal protractile mouth is specially designed to suck the substrate, sift what it considers edible and then gets rid of or expels the rest of the stew through the opercular openings. It is understandable that they could get confused and swallow some of the stew itself but it is not their primary food.

Recreate an Orinoco River biotope aquarium

If I were to recreate an Orinoco River Basin biotope aquarium, S. daemon would be one of the first fish I would think of. It is a common denominator fish in all the area. Planning an aquarium with such a predictable fish is quite convenient. No surprises, you know it will be confined to the aquarium bottom. To keep them successfully you will need a large aquarium, the longer the better. I will tell you how I envision it, as I write. My dream tank would be 2m long, or more, by 40cm wide or more, and 50cm tall or more. I would then add 4 or more inches of the substrate stew mentioned above, fine tuning the mix with 50% of 3mm grain white silica sand with 30% of a finer mesh silica sand + 20% very fine tan colored river sand. I would not place an undergravel filter. 

The decor would be extremely simple. I have always been in favor of putting extreme complexity into the basic decor itself and not on the aquarium decoration. I would then add a small amount of crumbled dry leaf litter over the stew; not too much though. I would then include a long narrow piece of drift wood in a slanted 45 degree angle in the back of the aquarium. I would want to leave as much open space in the front for the S. daemon to be able to school (yes they are schooling cichlids) as they sift the substrate.

If the drift wood is placed at an angle, it will have less contact with the substrate and leave more space for your fish to show you their incredible behavior. No rocks should be added to an Orinoco River aquarium setup, they are practically nonexistent in the basin. I would keep the filtration water current to a minimum, diffused or dampered as much as possible. Remember, they will do the vacuuming and will make sure the debris gets to the filter.

The light should be quite strong on 80% of the aquarium. I would try to find many small “narrow beamed” LED lights and fix them in an angle to a wood box cover over the aquarium. This will make the light look like sun rays entering the water in the same angle to the angle of the driftwood. These light rays will reflect off the debris that the S. daemon will lift as they feed, creating a backscatter look; amazing! Just thinking about this makes me smile. The thought of having an aquarium tenant that will constantly interact, change, and ad motion to something as inert and lifeless as substrate is just unbelievable.

Being able to see the flow and particles in motion in the water, through beams of light is just incredible, too. Detritus in the aquarium will never be this fun and interesting to watch. There are three keys in keeping S. daemon in aquariums. First you need acid soft water with a pH: under 6. Then you need soft water with a KH: less than 30mg/L (ppm), GH: less than 20mg/L (ppm), but the most important secret to keeping them is temperature. S. daemon like warm water and do not do well in temperatures under 26° Celsius being 29° Celsius an optimal temperature.

Sympatries & Feeding

The aquarium mates I would consider keeping with them would be large enough not to be eaten and at the same time nothing that competes with or disturbs their sifting underworld. Corydoras, Apistogramma, or any other bottom dwelling catfish or cichlids are out of the question. Mesonauta, Pterophyllum, or any other mid-level cichlid would be welcome. Large schooling tetras could also inhabit the long aquarium and will help add some movement to the mid top of the aquarium. Of course, I would also add one or two great glass cleaning plecos to keep my glass cleaning job to a minimum.

As food refers, I would feed our S. daemon earthworms, small crustaceans including inexpensive glass shrimps and of course, little by little teach them to eat flake or any other commercial dry food and include that in their usual diet as well.

Wow, I think I am going to get myself a Satanoperca daemon biotope aquarium, it sounds simply sophisticated!

This article has been published at:
• PFK – September 2014

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