Please, I'm not a "Dr." lol
You could have fooled me with all those long deep water fish names you've memorized and told everyone at the SF meeting a couple weeks back!

What an awesome presentation, though!
Okay, I was confused because you said Sprung and Delbeek talked about it which sounded like you had read it in a book. Well I am not sure that a bird dosage equates equally to a clam dosage but hopefully it worked.
I did not use the bird dosage. The dosage used in water fed to Pigeons is roughly 40-60 times the dosage I used. Racing pigeons, for example, are given water containing about 1000-1500 mg/gallon. That is why I recommend pigeon doxycycline sources; it is, by necessity of application and demand, dirt cheap from those sources.
What I said was that the dosage that is recommended for birds per kilogram body weight is approximately equal to that I am using per kilogram clam treatment water. Since a pigeon drinks a few tablespoons of water a day, the dosage put in their water must be much more concentrated to dose the proper amount considering their body size. Any animal is mostly water, including clams. The big difference is that I assumed a clam reaches an antibiotic concentration equalibrium with its holding water, whereas a bird simply holds its water (well mostly). It makes sense to me, then, that the surrounding concentration of antibiotic for a clam should be about the concentration recommended for the fluids of a bird's body.
Moreover, the dosage I used was not a guess based on birds anyway--that information I stumbled on later. Originally, I was reading <a href="http://www.malawicichlidhomepage.com/aquainfo/disease_4.html">on this fish disease site</a> that for Malawi bloat (a bacterial disease - gram negative), the author says "For minocycline we recommend 250mg/10 gallons of water. On day 2 change all the water and add the medicine again at the same dose for another 2 days." Minocycline is nearly identical to doxycycline, so I figured the dosage would hold for it as well.
Sorry for the confusion.