For example:
synodontis angelicus:
http://www.scotcat.com/factsheets/angelicus.html
http://www.planetcatfish.com/catelog/species.php?species_id=278
http://www.fishbase.se/Summary/SpeciesSummary.php?id=9536
So does it grow to 18cm, 24cm or 55cm??
I find this sort of thing often, makes it so difficult to decide if x fish is suitable for my tank or not!
Irene
The size of fish does seem to be effected by captivity. In some of the original aquatic fish encyclopedias the size listed for fish can be way off for what we know today because the conditions of their captivity led to poor growth. I have a marine aquarium book that lists captive sizes and natural sized for many of the more common fish. Some grow bigger and some remain smaller.
I think that fishbase is giving you the recorded size of wild caught fish and the aquarium sites are telling you have big the fish tends to get in captivity.
So would a 75g be big enough for a pair of syno angelicus then?
Irene
Fishbase sizes are from scientific papers and measurements, so while they may be hard to reach in captivity, those sizes are more accurate. The other ones tend to be more anecdotal, but might be more reflective of what ur likely to see in yuor tank.
I looked it up in my baensch aquarium atlas and it said 40cm. I find that atlas is fairly accurate with it's information. IF I were you, I'de just assume it gets the largest size and use that in you decision making. It could be that the measurements you have looked up are a range, so if you assume that it's going to reach full potential size because you take such good care of it, then you'll be ok. However if you get one, assuming it will only grow to 18cm, then you might be in the market for an even larger tank in the future when it exceeds this size!
Hmm, 40cm is seeming a bit big. Maybe something else would be better for that tank.
I would be interested in what each of the sites has to say about the discrepancies. Perhaps you could send off an e-mail to all of them and ask why the numbers are so different. I expect you would get an answer like the one mseguin posted but it would still be interesting to see what they have to say.
Remember that just because a fish is rated to get to a certain max size, it doesn't mean ALL specimens will get that big, or at a certain speed.
Some fish are so slow growing that you won't need to worry about their "max" size for many years.