34,000+
Known Fish Species
More than all other vertebrate groups combined
500M
Years Fish Have Existed
Fish predate trees. Fish predate insects. Fish predate almost everything.
71%
Earth Covered by Water
Fish are aware of this. Fish have made themselves at home.
0
Fish With Legs
Confirmed across all classified species. The Bureau checks.
Definition
What Is a Fish?
Fish are aquatic vertebrates. They are characterized by the presence of gills, fins, and in most cases scales. They are cold-blooded. They live in water. These are the defining characteristics the Bureau uses in classification. All criteria must be met. Tuna meets all criteria.
Bureau Classification Criteria
Aquatic Habitat
The subject must live in water. Freshwater, saltwater, or brackish water all qualify. Temporarily being on land does not disqualify. Permanently living on land does.
Fin Structure
Fins must be present. Pectoral, dorsal, caudal — specific configuration varies by species. A sword (see: Finding 008) is not a fin. The Bureau has confirmed this.
Gill Respiration
The subject must breathe through gills. Not lungs. Some fish have accessory breathing organs but must retain gills as the primary mechanism.
Vertebral Column
Fish are vertebrates. An internal bony or cartilaginous skeleton must be present. This distinguishes fish from invertebrates, which are a different matter entirely.
By the Numbers
Fish in Figures.
45
mph — Tuna Top Speed
Atlantic bluefin tuna can reach 45 miles per hour. This is faster than most land animals. Tuna does not think about this. Tuna simply swims.
1,500
lbs — Largest Tuna
Atlantic bluefin tuna can exceed 1,500 pounds. The Bureau notes this without concern. Large fish are still fish.
10
Years — Tuna Lifespan
Most tuna live 10–15 years. Some bluefin live 40 years. All of them are fish for the entirety of that time.
70+
Tuna Species
There are over 70 recognized tuna species. All of them are fish. The Bureau has not found a single exception. We have looked.
3°C
Warmer Than Ocean
Tuna can regulate their body temperature to stay warmer than the surrounding water. This is unusual for fish. It remains consistent with fish classification.
35M
Years as Fish
Tuna have been fish for approximately 35 million years. Their classification was not contingent on Bureau approval. We simply confirm what the record already shows.
“Fish were here before us, they will likely be here after us, and at no point during that interval have any of them had legs.”
Bureau of Fish Classification · Annual Summary, 2024
Common Misconceptions
Things That Are Not Fish.
Not a Fish
Jellyfish
No vertebral column. No gills in the traditional sense. No fins. The word “fish” in the name is a historical misnomer. The Bureau notes this without being able to correct centuries of common usage.
Not a Fish
Starfish
Echinoderm. Radially symmetrical. Has no vertebral column, no gills, no fins. Has five arms, which are also not legs, but also not fins. Not a fish. Also not a star.
Not a Fish
Whale
Mammal. Breathes air through lungs. Warm-blooded. Gives birth to live young. Nurse their young with milk. Whales are not fish. They live in the ocean. That is where the similarity ends.
Not a Fish
Dolphin
Also a mammal. See: whale. The Bureau is aware that dolphin is a common name for mahi-mahi in some regions. Mahi-mahi is under classification (Finding 007). The mammal called dolphin is not.
Historical Timeline
Fish Through History.
~500 Million Years Ago
Fish appear in the fossil record.
Early jawless fish emerge. They are already fish at this point. The Bureau did not exist yet. Fish did not require the Bureau.
~375 Million Years Ago
Some fish develop legs and leave the water.
These become the ancestors of all land vertebrates, including humans. The fish that stayed in the water remained fish. They made a different choice.
~35 Million Years Ago
Tuna appear.
Thunnus ancestral lineage emerges. Tuna is a fish from the beginning. This was not a close call. The Bureau is simply confirming what was always true.
2024
Bureau of Fish Classification founded.
The Bureau opens. Tuna is its first classification. Tuna is confirmed as a fish. 35 million years of existing as a fish is validated by 4 hours of deliberation. The process was thorough.
Individual Fish
Fish in the Record.
Facts about each fish currently in the Bureau’s classification record. Click any card to review the full case file. Closed cases have confirmed facts. Pending cases have preliminary observations that may or may not be reflected in the eventual finding.
Finding 001 · Closed
Tuna
Thunnus spp.
Classified: Fish
- Top speed: approximately 45 mph. Fastest of any classified fish.
- Has been a fish for approximately 35 million years.
- Body temperature can exceed surrounding water by up to 3°C. Unusual. Still a fish.
- Also a yummy dish. Secondary finding, equally final.
- Does not think about you.
Finding 002 · Closed
Mackerel
Scomber spp.
Classified: Fish
- Small to medium-sized. Travels in large schools.
- High in omega-3 fatty acids. The Bureau notes this without nutritional authority.
- Iridescent blue-green dorsal surface. Silver below. Striped markings.
- Closely related to tuna. Tuna classification did not automatically extend to mackerel. Mackerel was assessed separately.
- Second-fastest Bureau classification. Anchovy still holds the record.
Finding 003 · Closed
Anchovy
Engraulidae
Classified: Fish
- Small. Silver. Moves in very large groups called schools.
- Filter feeder. Eats plankton. Does not eat anything the Bureau classifies.
- Strong flavor. Commonly preserved in oil or salt. The Bureau classifies the fish, not the tin.
- Fastest Bureau classification: one session, eleven minutes, including time spent locating a pen.
- The panel was in agreement before the meeting began.
Finding 004 · Pending
Halibut
Hippoglossus spp.
Classification Pending
- Large flatfish. Can exceed 8 feet in length and 700 lbs.
- Both eyes migrate to the same side of the head during development. This is notable. It is not disqualifying.
- Lives near the seafloor in cold North Pacific and Atlantic waters.
- Preliminary assessment: consistent with fish classification. No anomalies beyond the eye situation.
- Expected resolution Q2 2025. Considered a formality.
Finding 005 · Pending
Sardine
Sardina pilchardus
Classification Pending
- Small. Silver. Oily. Comes in a can. These facts are noted without comment.
- Rich in nutrients. The Bureau does not make nutritional recommendations.
- Often packed in sardine oil, olive oil, or tomato sauce. The Bureau classifies the fish.
- Preliminary findings: consistent with fish classification.
- Panel has feelings about sardine. Feelings are documented. Classification will be professional.
Finding 006 · Pending
Salmon
Salmo salar
Classification Pending
- Anadromous: born in freshwater, migrates to ocean, returns to freshwater to spawn. This is remarkable behavior.
- Pink-orange flesh due to diet. Flesh color does not affect classification.
- Highly migratory. Significant commercial and cultural importance.
- Salmon is a fish. This is the Bureau’s informal assessment. The formal assessment is in progress.
- Expected resolution Q1 2025. The delay is paperwork.
Finding 007 · Pending
Mahi-Mahi
Coryphaena hippurus
Classification Pending
- Also known as dorado. Dorado says itself once. Mahi-Mahi says itself twice. Both refer to the same fish.
- “Mahi” means strong in Hawaiian. Saying it twice is an intensifier. The fish is apparently quite strong.
- Brightly colored: vivid blue, green, and gold. Described by field observers as “striking.”
- Warm ocean surface waters. Fast swimmer. Short lifespan of 4–5 years.
- Name delay resolved. Assessment underway. Expected resolution Q3 2025.
Finding 008 · Pending
Swordfish
Xiphias gladius
Classification Pending
- Has a sword. The sword is an extension of the upper jaw called a rostrum. It is used to stun prey.
- Species name means “sword sword.” The original taxonomists were committed.
- Can reach 14 feet and 1,400 lbs. Among the largest fish under active assessment.
- Highly migratory. Found in temperate and tropical oceans worldwide.
- The sword is not a leg. Confirmed. Internal memo on this point: resolved.
Finding 009 · Pending
The Unnamed Item
Unknown — Tip #47
Classification Pending
- Has fins. Fins are a positive indicator.
- Located in a body of water at time of observation.
- Breathing mechanism consistent with gill respiration.
- Also has something. The something is under assessment.
- The something is not a leg. This has been confirmed.
- Resolution timeline: unknown.
Finding 010 · Under Review
Whatever That Was
Unknown — Tip #83
Classification Suspended
- Located in a local waterway. Specific location on file.
- A photograph was submitted. The photograph is restricted.
- Assessment suspended following panel review of the photograph.
- One panel member on leave. Classification requires full panel.
- The Bureau is not prepared to share further facts at this time.