The 声纳药水 is a 增益药水 which grants the 声纳 增益 when consumed. When 钓鱼 while under the effects of the potion, the name of what you will catch will appear above the lure when it is bitten. The name will not be shown however, if the item pickup text is disabled in Settings. This lasts for 4 minutes, but can be cancelled at any time by right-clicking the icon. This potion is especially useful as it allows the player to not waste 鱼饵 on unnecessary fish as the cast can be left in the water until another fish bites at the line.