If you have the book “Saving Sick Fish” by Erik Johnson DVM you know it’s backed up by a web site with further reading. A considerable amount EXTRA is available for free with “Codes”. 
In the website you’ll find further resources; pages and posts that entitled something like: “Resource J3”, for example.
Resource J3 <= A working example*
The simple, three character password (BFG case-sensitive) for the Resource comes from a Code Chart on the last page of the book “Saving Sick Fish” you’ve probably already bought. “Resource J3”. Specifically, look up the three-character code found in the square labeled “J3” Which is “BFG” by the way. Super easy.
Resource codes are CASE SENSITIVE.
All are alphabetical. Not numeric except resource A2.
There are 48 new, protected resources, and 48 codes to unlock them.
These resources can include printable downloadable e-books, charts, VIDEOS (lots of new videos), downloads, referrals, or bonuses. MOSTLY things to elevate the book from “Saving Sick Fish” to a greater “Understanding Sick Fish” without killing more trees, or costing you any more money.
*This example has an old video. Not a new one. All the actual resources contain new not-recycled information.