BROLGA
grep ^.rolg.$ /usr/share/dict/wordsbrolgabrol·ga">brol·ga">brol·ga   [brol-guh] nouna large Australian crane, Grus rubicunda, with silvery-gray plumage and a red patch on the head, noted forits elaborate courtship dance.
walrus
monkey
pigpen
Some six letter words with FF in the middle are:wafflebafflebufferduffermufflepifflesufferduffelpuffindiffer
grep ^.rolg.$ /usr/share/dict/wordsbrolgabrol·ga">brol·ga">brol·ga   [brol-guh] nouna large Australian crane, Grus rubicunda, with silvery-gray plumage and a red patch on the head, noted forits elaborate courtship dance.
grep ^.rolg.$ /usr/share/dict/wordsbrolgabrol·ga">brol·ga">brol·ga   [brol-guh]nouna large Australian crane, Grus rubicunda, with silvery-gray plumage and a red patch on the head, noted forits elaborate courtship dance.
The animal you're looking for is "strick," which refers to a type of fish, but it seems you might be looking for a more common animal. The word "lizard" fits the criteria of having six letters with "str" in the middle. However, "str" specifically in the middle of a six-letter animal name is quite rare. If you're open to a broader interpretation, "ostrich" could also work, though it has seven letters.
walrus
6
Shrimp
Salmon
dog
monkey
spiders
pigpen
rabbit has 6 letters R-A-B-B-I-T