From Crochet at About.com:
Bat-fish Free Chart
An Original Designed by Sandi Marshall

These charts are free for your own personal use only.

To make a crocheted background to cross-stitch the bat-fish on: Starting chain for single crochet is 51. Starting chain for afghan stitch is 50. Make 50 rows.

Working the Chart in Filet Crochet For a 4 dc mesh, beginning chain is 151, plus chain 3, (which will count as first dc of first row), plus chain 2 (which is the ch-2 of first open mesh), for a total starting chain of 156 chains. Begin by working a double crochet in the 9th chain from the hook. Follow chart for placement of solid mesh and open mesh for each row. For a refresher on how to do open and solid mesh, see Basics link below. Chart is worked starting at the bottom right; work first row right to left. Second row is worked left to right. Continue alternating row directions in this same manner, following chart. Approximate finished sizes in filet crochet (once through one chart, worked in 4 dc mesh): With size 5 thread: (320 yards) and a size US 4 steel hook, finished size is about 13.9 inches x 15.8 inches. With size 10 thread: (285 yards) and a size US 7 steel hook, finished size is about 11.5 inches x 12.5 inches. With size 20 thread: (268 yards) and a size US 9 steel hook, finished size is about 11 inches x 12 inches. With size 30 thread: (250 yards) and a size US 11 steel hook, finished size is about 10.5 inches x 11.5 inches. With fingering/baby weight yarn: (625 yards) and a size US F hook, finished size is about 35 inches x 36 inches. With sport weight yarn: (725 yards) and a size US G hook, finished size is about 40 inches x 41 inches. With worsted weight yarn: (825 yards) and a size US I hook, finished size is about 45 inches x 46 inches.

Gauge:
With size 5 thread: 5 squares = 1.4 inches, 5 rows = 1.6 inches
With size 10 thread: 5 squares = 1.2 inches, 5 rows = 1.3 inches
With size 20 thread: 5 squares = 1.1 inches, 5 rows = 1.2 inches
With size 30 thread: 5 squares = 1 inch, 5 rows = 1.1 inches
With fingering/baby weight yarn: 5 squares = 3.5 inch, 5 rows = 3.6 inches
With sport weight yarn: 5 squares = 4 inch, 5 rows = 4.1 inches
With worsted weight yarn: 5 squares = 4.5 inch, 5 rows = 4.6 inches

Basics in How to Do Filet Crochet, here: http://crochet.about.com/library/weekly/aa050298.htm

You may print out one copy of this page for your own personal use (not-for-profit use of the pattern and of finished items which include my design within the item). Do not copy further, do not post anywhere on the Internet or otherwise redistribute the contents of this page (this includes the images). Even if you didn't charge for it, it would be a copyright violation to make reproduced copies of a copyrighted pattern available to others without the permission of the person or company that owns the copyright for that pattern. If others would like to have the patterns, do not give them photocopies, scans or other forms of reproduced copies of the charts but instead please give them the URL of this page so that they may come here for themselves. If you like my patterns and would like me to continue creating new ones and making them available to you as free patterns on the Internet, then please follow these simple guidelines. Thank you.

URL for this page is http://crochet.about.com/library/nbfish1.htm

Questions about copyrights? See:
US Government Copyright FAQ - http://www.loc.gov/copyright/faq.html
Copyright Myths Explained - http://www.templetons.com/brad/copymyths.html

You may also give out the following URL for anyone who would like to have this bat-fish chart: http://crochet.about.com/library/blbfish1.htm - Thank you!

For many more charts, see: Index of Free Charts: http://crochet.about.com/library/blfreecharts.htm
Crochet Homepage: http://crochet.about.com