 Thread @-@ sail filefish grow to a maximum adult length of about 30 centimetres ( 12 inches ) . The first dorsal fin is a strong retractable ( folding backwards ) spine . The second dorsal fin and anal fin are soft . They have comparatively small pectoral fins and truncated , fan @-@ shaped tail fins . The dorsal and anal fins are colorless . Their second dorsal , anal and caudal fins rounded . In males , 1 @-@ 3 soft dorsal fin rays extended as filaments ; the first ray has a particularly long thread . The fish have a small abdominal spike . The fish are colored from light brown , to grayish- to light greenish @-@ beige , and are slightly patterned with irregular , broken stripes that range from medium brown to blackish . 
 Thread @-@ sail filefish grow to a maximum adult length of about 30 centimetres ( 12 inches ) . The first dorsal fin <a href='drop_aux' title='1'><mark>is</mark></a>a strong retractable ( folding backwards ) spine . The second dorsal fin and anal fin <a href='drop_aux' title='2'><mark>are</mark></a>soft . They <a href='got' title='3'><mark>have</mark></a> comparatively small pectoral fins and truncated , fan @-@ shaped tail fins . The dorsal and anal fins <a href='drop_aux' title='4'><mark>are</mark></a>colorless . Their second dorsal , anal and caudal fins rounded . In males , 1 @-@ 3 soft dorsal fin rays extended as filaments ; the first ray <a href='got' title='5'><mark>has</mark></a> a particularly long thread . The fish <a href='got' title='6'><mark>have</mark></a> a small abdominal spike . The fish are colored from light brown , to grayish- to light greenish @-@ beige , and are slightly patterned with irregular , broken stripes <a href='null_relcl' title='7'><mark>that</mark></a>range from medium brown to blackish . 
Thread @-@ sail filefish grow to a maximum adult length of abt 30 centimetres ( 12 inches ) . The first dorsal fin a strong retractable ( folding backwards ) spine . da second dorsal fin and anal fin soft . They got comparatively small pectoral fins and truncated , fan @-@ shaped tail fins . Tdadorsal and anal fins colorless . Their second dorsal , anal and caudal fins rounded . In males , 1 @-@ 3 soft dorsal fin rays extended as filaments ; the first ray got a particularly long thread . Thdaish got a small abdominal spike . The fish are colored from light brown , to grayish- to light greenish @-@ beige , and r slightly patterned with irregular , broken stripes range from medium brown to blackish .