Bucktooth tetra are well known for eating the scales off of fish that are too big for them to eat. I have no personal experience with them but with a HEAVILY planted tank you MIGHT be able to put a pleco of some kinda in there, something 7" or less. If you do go that route, or any route, have plans to rehome the new fish if you have to.
"This is not a community fish, and is best kept in a species setup. It will relentlessly attack any silver-coloured or shiny tankmates, stripping them of scales and fins very quickly. Even larger, predatoryspecies are not safe. Scaleless and non-reflective fish are generally left alone. Success has been had keeping Exodon alongside various loaches, Loricariids and some larger characins such as Anostomus. The situation will always be somewhat unpredictable though. It’s best to add the Exodon last as they may see any new additions as food, and as with most predatoryspecies they tend to bite first and ask questions later."
"Make sure you buy a sufficiently large group of these. A minimum of a dozen is usually recommended, but buy as many as the tank can house. In a tank like the one described above a group of 25-50 would not be an unreasonable number. If kept in smaller groups, they tend to pick one another off until only a single fish remains. In large shoals, no individual can be targeted and it is usually only sick or unhealthy specimens that are killed, although occasional losses should still be expected. The interaction of a big group is fascinating to watch, as they squabble amongst themselves constantly. Feeding time in particular is quite a sight. Buy the entire group at the same time as new additions are usually attacked."
The only gravel-sifters I could recommend with these exodons would be snails such as Malaysian Trumpet or the larger Rabbit Snails. Both are substrate tunnelers and they're livebearer species so, no messy gelatinous masses all over the tank.
Forget about loaches. My brothers exodons harassed his clowns and yogi loach to the point where they stopped eating. He eventually had to take them out and put them in his angelfish tank.