Computed Tomography (CT) scanning, a familiar diagnostic tool in human medicine, is now being applied to fish. This technology offers a non-invasive way to create a clear, three-dimensional view of internal structures without dissection. The use of CT scans on aquatic life is expanding our understanding of their biology and improving how their health is managed.
Why Scientists and Vets Scan Fish
The application of CT scanning in aquatic science and medicine serves multiple purposes, from ecological studies to individual animal care. For researchers, these scans are a tool for taxonomy, helping to classify species by revealing subtle differences in skeletal structure. This method allows scientists to study rare or delicate specimens without causing damage. An initiative known as the #ScanAllFishes project, for example, aims to create a digital library of 3D images of all known fish species.
This digital archive supports the study of evolutionary biology by allowing detailed comparisons of anatomical features across species. Scientists can analyze how different fish are related and how they have adapted to their environments over time. For veterinarians, CT scans are used to diagnose and treat ailments in fish, particularly high-value individuals like ornamental koi. The technology can detect tumors, internal injuries, and swim bladder issues.
Museums and research institutions also use this technology to create permanent digital records of their collections. By scanning a specimen, they create a high-resolution 3D model that can be studied by anyone, anywhere. This process preserves the physical specimen while making its anatomical data widely accessible for education and research.
The Fish Scanning Process
The procedure for scanning a fish depends on whether the subject is living or a preserved specimen. For a live fish, the process begins with anesthetization in water containing a mild anesthetic agent. The fish is then positioned on a custom-built platform designed to keep it stable.
To ensure the fish can breathe, a system gently pumps water over its gills throughout the scan. For deceased specimens from a museum collection, the process is simpler. They are wrapped in ethanol-soaked cheesecloth to prevent dehydration and arranged on the scanner bed, sometimes with multiple specimens being scanned at once.
Once positioned, the fish is moved through the gantry of the CT scanner. The machine rotates around the fish, taking hundreds of X-ray images from various angles. A computer then compiles these individual images, or “slices,” into a comprehensive, three-dimensional digital model.
Visualizing the Unseen World of Fish
The data generated from a CT scan offers a detailed look into the internal anatomy of a fish. These scans reveal the skeletal system, including every bone and cartilaginous structure. The precise placement of internal organs, the brain’s structure, and the vascular system are all made visible. This detail allows for the identification of parasites or diseases that would be impossible to see otherwise.
A primary outcome is the creation of interactive 3D digital models. Researchers can manipulate these models on a computer, rotating them to view from any angle and digitally dissecting them layer by layer. These digital files can even be used to create physical replicas through 3D printing, enabling hands-on study.
This technology has led to new discoveries. For instance, by examining 3D models of a fish’s jaw and skull, scientists can better understand the biomechanics of how it feeds. In some cases, scans have revealed unique internal features that have led to the identification of entirely new species.