I enjoy pet fish and have kept a variety of smaller and larger species. I am particularly fond of cichlids.
There are many species of synodontis, and there are many hybrids and crossbreeds between the species which pop up as well, quite often in pet shops. Synodontis appear to crossbreed quite happily and readily, much to the chagrin of purists who do not approve of such abominations.
Is My Fish a Hybrid?
Unless you have a very common species, it may be difficult to tell if what you have is a hybrid or not. There are currently well over 100 different identified species of synodontis, and more than one syno has been misidentified as a hybrid when it was, in fact, a new species.
Whether you care if your synodontis is a hybrid or not will depend on whether you intend to attempt breeding (a very noble goal indeed, given the difficulty of breeding synodontis), or whether you are paying a premium for a 'pure' fish.
How Do I Identify 'Pure' Fish?
If you are trying to identify whether or not a synodontis is pure, pay special attention to fin shape, size and coloration, to the nature of the barbs around the mouth, to the overall body shape of the fish and to its markings. If your synodontis seems to have the characteristics of more than one species, there is a fairly decent chance that it is a hybrid.
If you really want to know, this article from Planet Catfish is an excellent in-depth guide to identifying hybrid synodontis.
A Guide to the Different Species
These are synodontis with shark-like fins, which have made them very popular indeed. They can command quite high prices both in pet stores and out of them. These synos grow to around 12 centimeters, so they are not terribly large, and if you have the funds, you can quite happily keep several of them in a 90-gallon tank.
They are also known as the cuckoo synodontis as they have a habit of eating the eggs of other fish and depositing their own in place for the other fish to tend as they grow.
A much deeper-bodied synodontis, the Synodontis eupterus is also known as the featherfin squeaker because of its beautiful feathered dorsal fin and the fact that it can produce a high-pitched squeaking with it. These fish grow up to 20 centimeters, though 15 to 17 is more common. They have been reported as being more aggressive than other catfish.
A native of Lake Malawi, Synodontis njassae is a pretty catfish with lovely coloration which can vary widely from fish to fish. Some specimens may have many spots covering their body, while others have but a few. Some keepers break these into large- and small-spotted varieties. They grow to around 20 centimeters.
Monsters, these synodontis can grow over two feet in length. They are not at all recommended as pets unless you have a very, very large fish tank. Even 100 gallons won't cut it with one of these fish when they reach maturity.
A peaceful synodontis species, these do not grow much over 12 centimeters. Unlike other species of synodontis, these have been bred in captivity relatively easily, but they prefer to live and spawn in groups, so a pair may not spawn alone. These are easily confused with multipunctatus; however, they sport a white trim which is not present in the multipunctatus. They tend to be quite expensive.
Quite common, these synos reach just four inches in length, which makes them the perfect catfish for a smaller aquarium. They are known widely as the 'upside down catfish'. They reach around 10 centimeters (or four inches) and are very pretty and entertaining to watch as they defy gravity. It is best to keep this type of synodontis in groups of three or more.
jfm on December 30, 2013:
the syndontis catfish have all kinds of different behaviors even if their the same kind
Marsha Hall on October 06, 2013:
My synodontis was 2" long in 1986! No typo...1986! I know because in 11/'86 we took our Appaloosa stallion to the World Champ Show 100's of miles away, for a week. Had so many fish I got an amateur to feed while I was gone but worried what syno would eat. Never let an amateur feed pellets! The fish lucked out as the amateur quit the job after 1 day (went deer hunting). This synodontis is still going as of 10/6/2013...27 yrs later!
Stephanie Giguere from Worcester, MA on January 04, 2013:
I love my S. nigriventris! He has so much personality. Nice Hub, voted up!
LeeV on July 31, 2011:
I recently set up an African Cichlid tank and got a syno to scavenge, but as far as I can tell, it never goes to the bottom of the tank. When I feed, it comes to the top and swims around upside down eating flakes off of the surface. Fascinating.
joey geist on May 18, 2011:
i have a hybrid syno and it is about 6 inches long and spoted all over and a very shy fish. it will come out for frozen brime shrimp or small pieces of shrimp.
Tamarind on April 06, 2010:
I always thought there was something wrong with them when they swim upside down, but I have seen whole tanks of them do it. Funny things. These are very neat fish. Thanks for the info.
Bunniez (author) on October 14, 2009:
How odd, as far as I can tell with catfish, they quite often don't seem to worry about what side is up anyway, mine spends happy days hanging upside down inside a tall hollow log like a bat!
rmr from Livonia, MI on October 14, 2009:
I think these are among the most beautiful aquarium fish. I particularly like the way the Nigriventris is built to look like it's swimming upside down. Strangely, I had one that actually did swim upside down, so it always appeared to be rightside up.I never figured out why, but he lived that way for 5 or 6 years.