How about people who have had gars with broken backs list what the tankmates were?
Shortnosed with Shortnosed
Shortnosed with longnosed
Shortnosed by it's self no tank mates
Shortnosed with (Fathead) Rosy minnows (go figure)
Shortnosed in a bucket by it's self (I'm still at a loss on this one)
Longnosed by it's self no tankmates
Longnosed with Central longear sunfish
Longnosed with Black bullhead
Longnosed with Shortnosed
Florida by it's self no tankmates
Florida with Florida
Florida / spotted with Shortnosed
Florida/spotted with Polypterus delhezi
Gator with Shortnosed
Thats about it for me... I generally keep these fish in species only tanks, have long ago identified this problem and always taken steps to avoid this. Being primarily a gar keeper and having not so much of an interest in "postage stamp" collections I really have not mixed these fish much.
Majority of the problems I have advised on (Hundreds by now) have involved cichlids, plecos, synodontis and Aros. to a lesser degree other large catfish species such as Ritas, RTC, channel cats, bullheads or TSN.