People who have a heart attack sometimes experience heart muscle damage. As a result, many live with heart failure and may require a heart transplant in the future. But what if there was a way for human hearts to heal themselves? Scientists say an exotic fish could perhaps hold clues to making such an occurrence a reality. The Mexican tetra fish, which lives in freshwater, can, quite amazingly, repair its own heart. Popular with aquarium owners because of its unique coloring, the tetra fish has many different species, most of which can heal their own hearts following damage. To understand how the tetra fish do this, a team of researchers from the University of Oxford in the UK travelled to the Pachón cave in Mexico to study a tetra subspecies, the “blind cave tetra”. This remarkable fish has not only lost its ability to see, but also its color. Moreover, it can no longer regenerate heart tissue. By studying the blind cave tetra alongside other species of tetra, the team of researchers was able to create genetic profiles for both, allowing them to better understand what gives the tetra its amazing heart regeneration abilities. The team, led by Dr. Mathilda Mommersteeg, an associate professor at the University of Oxford, identified three separate genomes relevant to the tetra’s self-healing. Further analysis revealed two genes, lrrc10 and caveolin, were far more active in the river tetras. “A real challenge until now was comparing heart damage and repair in fish with what we see in humans. But, by looking at river fish and cave fish side by side, we've been able to pick apart the genes responsible for heart regeneration,” said Dr. Mommersteeg. Going forward, the research team hopes it may be possible to develop a way for heart attack patients to repair their own heart tissue.