Having lost our 2.5'-er earlier this year to a freak occurrence (killed by synodontis - mid second page https://www.planetcatfish.com/forum/viewtopic.php?f=9&t=41670&hilit=eupterus&start=20 ), we have been left with four iridescent shark catfish, all of which are ~2' now.
All of them have always been and continue to be in the same 4500 gal tank with the same synos, FWIW...
Two of the IDS I got last Sept 2016 at ~3"-4" from Aquarium and Reef Center in Cape Coral, FL. They have grown fast having put on ~20" in 15 months. So they would belong to the fast-and-relatively-large-growing fraction of IDS we get in the trade, see these informative threads for more
-- https://www.monsterfishkeepers.com/forums/threads/id-sharks-theories.505668/
-- https://www.monsterfishkeepers.com/forums/threads/heavily-stunted-id-shark-help.592861/ -- see a collection of links in my post #9
-- https://www.monsterfishkeepers.com/forums/threads/id-shark-housing.574589/
Another two had been rescued by a prior owner and are much older, I guesstimate about 10 years. They have not grown much in my care, having been with me for 4-5 years now, maybe a bit. One is missing both eyes. I was told it was housed with a banded leporinus by the original owner (so I am at least a third owner in line) for a long time just fine until one day the lepi has gone mad and attacked the IDS, stripping it of fins, taking both eyes out, and latching onto its stomach (can still see the spot). The IDS miraculously survived that horrific attack.
Here they are today in 4500 gal:
All of them have always been and continue to be in the same 4500 gal tank with the same synos, FWIW...
Two of the IDS I got last Sept 2016 at ~3"-4" from Aquarium and Reef Center in Cape Coral, FL. They have grown fast having put on ~20" in 15 months. So they would belong to the fast-and-relatively-large-growing fraction of IDS we get in the trade, see these informative threads for more
-- https://www.monsterfishkeepers.com/forums/threads/id-sharks-theories.505668/
-- https://www.monsterfishkeepers.com/forums/threads/heavily-stunted-id-shark-help.592861/ -- see a collection of links in my post #9
-- https://www.monsterfishkeepers.com/forums/threads/id-shark-housing.574589/
Another two had been rescued by a prior owner and are much older, I guesstimate about 10 years. They have not grown much in my care, having been with me for 4-5 years now, maybe a bit. One is missing both eyes. I was told it was housed with a banded leporinus by the original owner (so I am at least a third owner in line) for a long time just fine until one day the lepi has gone mad and attacked the IDS, stripping it of fins, taking both eyes out, and latching onto its stomach (can still see the spot). The IDS miraculously survived that horrific attack.
Here they are today in 4500 gal: