Pets

List of Named pets in the anime.

Gu
Gu (具) is a tanuki (Japanese raccoon dog). Renge feeds and considers Gu her pet (even though it's probably a wild animal.)

Salt
Salt (塩) is a crab that Renge catches in the river and wants to keep as a pet. Natsumi comments, "You don't have much of a gift for naming things do you?". Kazuho convinces her to set it free.

In the manga Renge catches Salt again (supposedly the same crab) in the winter and puts it in an aquarium in her house.

Pechi
Pechi (ペチ) is Hotaru's pet corgi.

In the manga, Pechi appears to be much smaller, maybe even a different breed.

Renge once called Pechi "Hiza-Kakkun" (膝カックン/ひざかっくん), which means a prank making someone's knees bend from behind using your knees (like this).

Pechi's voice is played by Akiko Hiramitsu, the voice actress for Yukiko Koshigaya (Koshigaya siblings' mother).

Flatty-san
Flatty-san (ひらたいらさん) is the name Renge gave to a bunch of triops shrimp that the girls collected from a river. She keeps them in an aquarium in the school and is the sole caretaker for them. She also keeps an observation journal on them.

The name "Hirataira-san" is a pun of "hiratai" (ひらたい/平たい, adjective "flat") and a manga artist Taira Hara (はらたいら, "Hara Taira" in Japanese name order).

Sonohigurashi
Hand to Mouth (その日暮らし) is a cicada that Natsumi lures out of its hole by pouring water into it. Renge calls it "Hand to Mouth" (it's a rather hard word to translate, essentially it means "a carefree existence/living life day-by-day").

This name is a pun of "," a kind of cicada that is very common in Japan. It is not certain if Sonohigurashi is really a higurashi or another kind of cicada, though.

Hikarimono Boss
Hikarimono Boss (光りもの親方) is a huge common carp that Natsumi catches when the girls go fishing. They bring the carp to Natsumi's and put it in a pond. Later Renge decides to name it "Hikarimono Boss". In a later episode, the carp is referenced, so it is safe to assume that it still lives in the pond at Natsumi's house.