Games like Cozy Aquarium
Games like Cozy Aquarium include Stardew Valley, DAVE THE DIVER, Mini Cozy Room: Lo-Fi, Unpacking, and Chill with You : Lo-Fi Story. We matched them by the tags players give Cozy Aquarium on Steam (Cozy, Relaxing, Underwater, Utilities, and Casual): closest matches first, and among equally close ones the better-known games.

Stardew Valley
Shared: Relaxing · Pixel Graphics · Life Sim

DAVE THE DIVER
Shared: Relaxing · Pixel Graphics · Casual

Mini Cozy Room: Lo-Fi
Shared: Cozy · Relaxing · Utilities

Unpacking
Shared: Relaxing · Casual · Pixel Graphics

Chill with You : Lo-Fi Story
Shared: Relaxing · Casual · Utilities

Cast n Chill
Shared: Relaxing · Cozy · Pixel Graphics

Spirit City: Lofi Sessions
Shared: Cozy · Relaxing · Casual

Hozy
Shared: Cozy · Relaxing · Casual

My Dream Setup
Shared: Relaxing · Cozy · Casual

Sticky Business
Shared: Relaxing · Casual · Indie

Leaf it Alone
Shared: Relaxing · Cozy · Casual

ABZU
Shared: Relaxing · Underwater · Casual

Ropuka's Idle Island
Shared: Relaxing · Cozy · Casual

DrainSim
Shared: Relaxing · Casual · Underwater

Whisper of the House
Shared: Relaxing · Casual · Pixel Graphics

Paralives
Shared: Life Sim · Indie · Relaxing

Palia
Shared: Cozy · Life Sim · Relaxing

Tiny Glade
Shared: Relaxing · Cozy · Casual

Minami Lane
Shared: Relaxing · Casual · Cozy

SUMMERHOUSE
Shared: Relaxing · Casual · Pixel Graphics

Dressmaker
Shared: Cozy · Relaxing · Casual

The Sims™ 4
Shared: Life Sim · Relaxing · Casual

Tiny Bookshop
Shared: Cozy · Relaxing · Casual

Hello Kitty Island Adventure
Shared: Cozy · Relaxing · Casual