Do fish ever get thirsty?
The Real Answer
Freshwater fish don't drink water voluntarily — it flows into their bodies through osmosis and they excrete the excess through their gills and urine. Saltwater fish do drink water constantly because the salt in the ocean pulls water out of their bodies, so they need to actively replace it. Whether they experience 'thirst' as a sensation is unknown, but the biological mechanism works differently than in land animals.
You never order water because you ARE in the water. You're soaking in your beverage 24 hours a day. A fish is a person who never leaves the pool.
Why People Ask This
This is a shower-thought question that hits harder the more you think about it. It exposes a weird gap in how we think about water — we assume thirst is universal, but fish live in the very thing we get thirsty for. The freshwater vs. saltwater distinction surprises almost everyone, and suddenly you realize you've been projecting human needs onto something that operates on completely different rules.