If placed within the normal helmet slot (meaning not vanity slot), the breath bar will appear and you will start to drown; however, with an activated Breathing Reed or a Gills Potion, you will not drown. The Neptune's Shell accessory won't have its effect, although it will still function properly underwater. This makes it harder to survive when it is equipped in the armor slot and is recommended to be in the social slot.
If placed within the social equip slot, the breath bar will not appear and you will not drown. This is, of course, because social slot equipped items do not give any effect. When used in conjunction with the Gills Potion, the fish bowl allows for breathing both above and under water. Prior to 1.2, this was one of the only ways to be able to breathe in both locations.
When the player walks, the two fish move around the bowl. The faster the player walks the faster the fish will move. The fish do not move if the player is using an item.
When you equip a Fish Bowl, your hair is removed. This is most easily noticed when you take damage; when the transparency affects you, you will be able to see that you have no hair. Don't worry, however, as your hair will return to you as soon as you take off the fish bowl.
On 1.0.4 update Fish Bowls texture changed, but it still uses old texture when worn on head.
Fish Bowl can be placed on flat surface items or ground, and it will have only one gold fish swimming in it.