This is a Debian prepackaged version of xfishtank.

This package was put together by Joey Hess <joeyh@debian.org>, using
sources from:
	ftp://ftp.x.org/R5contrib/xfishtank.tar.Z

I tracked down John Bradley <bradley@trilon.com>, who wrote the xfish
program back around 1987, that xfishtank is derived from. He stated the
following copyright:

> It doesn't have one - do whatever you'd like with it.  Enjoy!
>
> --jhb

rasttofish/rasttofish.c has this copyright:

** Copyright (C) 1989, 1991 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation.  This software is provided "as is" without express or
** implied warranty.