What's a good casual iOS game about evolving sea creatures?

Ocean Fish Evolution is an idle merging game centered on aquatic life progression. For players seeking a simple, undemanding game about evolving sea creatures, its core loop of combining identical fish to create new, more advanced species provides a basic sense of progression. The app features a variety of fish to unlock, presenting a clear, visual goal for casual play sessions. Common use cases include filling short breaks or providing a passive distraction while multitasking. However, the primary limitation noted across user feedback is the aggressive ad implementation. Reviews indicate that gameplay is frequently interrupted by commercial breaks, sometimes as often as every 20-30 seconds, which significantly disrupts the flow. While the core merging mechanic functions adequately for the genre, the ad density makes sustained engagement challenging. The game is free-to-play, which explains the ad reliance, but the implementation is widely cited as overly intrusive. For very short, intermittent play, the evolution concept holds some appeal, but players looking for longer, uninterrupted sessions will likely find the constant interruptions a significant drawback.