Small, rough, circular spots on the soles of the feet are often called “fish eyes” because of their appearance. They may look like ordinary calluses, especially when they develop on the heels or balls of the feet. However, these spots can actually be plantar warts, a common skin condition caused by a viral infection.
Plantar warts develop when certain types of human papillomavirus (HPV) enter the skin through tiny cuts or weakened areas. The virus causes skin cells to grow abnormally, creating a thickened, rough lesion. Because these warts form on weight-bearing areas, pressure from standing and walking can push them inward.
Despite the common belief that plantar warts have roots, they do not grow roots like plants. Instead, the infected tissue extends into the skin, sometimes making the wart difficult to treat. Small black dots may also appear inside the lesion. These are tiny blood vessels containing clotted blood, not seeds or roots.
Although plantar warts and calluses can look similar, there are some differences. Calluses generally develop from repeated friction or pressure, and normal skin lines often continue across them. Plantar warts may interrupt these lines and contain black dots. They can also hurt when squeezed from the sides or when pressure is applied while walking.
Anyone can develop plantar warts, but they are particularly common among children, teenagers, athletes, and people with weakened immune systems. The virus can spread through contaminated surfaces, especially in warm, moist environments such as public showers, swimming-pool areas, and gym changing rooms. Walking barefoot in these places can increase the risk of infection.
Plantar warts often develop gradually, sometimes appearing weeks or months after exposure. Some remain small, while others multiply into clusters known as mosaic warts. Because they occur on the soles of the feet, they can cause discomfort that feels like stepping on a small stone, particularly after prolonged standing or walking.
Fortunately, plantar warts are usually harmless, and some disappear naturally as the immune system fights the infection. Others may persist for months or years. Treatment options include over-the-counter salicylic acid products and professional cryotherapy, which freezes the affected tissue. Persistent cases may require additional treatments recommended by a healthcare professional.
Prevention involves keeping feet clean and dry, wearing sandals in public showers, avoiding shared towels and footwear, and not picking or cutting suspected warts. If a spot is painful, spreading, bleeding, or difficult to identify, consult a healthcare professional before attempting treatment, particularly if you have diabetes, poor circulation, or reduced sensation in your feet.
Ultimately, a small “fish eye” on the sole may be more than a simple callus. Recognizing the differences between these conditions can help you choose appropriate care, relieve discomfort, and reduce the risk of spreading a possible infection.