Here's something most fish owners never think about: your fish almost certainly has teeth. And those teeth can get sick. Just like yours.
We spend a lot of time thinking about water quality, feeding schedules, and tank décor—but oral health? Almost never. The truth is, fish have some of the most fascinating and varied dental anatomy in the entire animal kingdom, and understanding it can make you a much better fish keeper.
Fish Have Teeth in Surprising Places
Here's where it gets genuinely wild. Depending on the species, your fish might have teeth in any—or all—of these locations:
- In their throat: Many common fish like goldfish and koi have no teeth in their mouths at all—instead, they have pharyngeal teeth deep in their throat that grind food before it's swallowed. You'd never see them without a microscope.
- On their tongue: Some fish species have teeth fused directly to their tongue—a structure so alien it barely resembles what we'd call a tongue at all.
- Multiple rows at once: Piranha-like fish can have several rows of interlocking teeth, replacing worn ones throughout their lifetime.
- Fused into beaks: Parrotfish have teeth fused together into a beak strong enough to bite off chunks of coral reef—they're essentially swimming with a power tool in their mouth.
🐟 Fun Fact: The tiny Pacu fish, sometimes kept as a pet, has teeth that are startlingly human-like in appearance—flat, squarish molars designed for crushing nuts and seeds. Seeing them up close is genuinely unsettling.
Why Your Tank Fish's Oral Health Matters
For pet fish—especially large cichlids, goldfish, koi, and carnivorous species—oral health problems are more common than most owners realize. And because fish can't tell you something hurts, the signs are easy to miss.
Fish with dental or mouth problems often show it through their behaviour first: dropping food repeatedly, favouring one side of the mouth, becoming suddenly less interested in eating, or rubbing their mouth against tank surfaces. These aren't quirks—they're communication.
Bacterial infections of the mouth (often called "mouth rot" or ulcerative stomatitis) are among the most treatable conditions in fish—but only if caught early. Left alone, an oral infection can spread rapidly and affect overall health and immunity.
The Connection Between Water Quality and Oral Health
Here's the surprising link most fish owners don't make: water quality is directly tied to your fish's oral health. Poor water conditions—high ammonia, low oxygen, incorrect pH—weaken the mucosal lining of the mouth, making it far easier for opportunistic bacteria to take hold.
Think of it like immune health. A fish living in pristine water has a robust, well-functioning mouth lining that resists infection naturally. A fish in compromised water is constantly fighting just to keep its baseline defenses up—and the mouth is often the first place that shows.
This is why "my fish stopped eating" is such a common presenting complaint—and why the answer isn't always in the food. Start with the water. Test it. Then look closer at the mouth.
Takeaway: Fish have some of the most remarkable dental anatomy on the planet—and their oral health is more connected to their tank environment than most owners ever realize. Healthy water = healthier mouths.
