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A family tree of the perch-like fishes

A shape is not a family.

The smallmouth bass, the red snapper, the grouper, the tripletail and the peacock bass all wear the same build — deep body, big mouth, spiny front fin, an ambush predator sitting in cover. That build has been invented over and over, in different parts of the tree, by fish that are only distant cousins. So this page places them by anatomy and DNA, and never by the outline or the name. It is the only way to find out which look-alikes are actually related to the fish you caught.

— valid species of fishes are on record, and — of them are bony fishes — well above the 28,000 usually quoted, which is a figure from decades ago. The families on this page hold — of those, about one in ten. The rest sit on branches this page does not draw.

What “bass-shaped” means

It is a description of a job, not of a family. A fish that hunts by ambush in a three-dimensional tangle — weed, reef, rock, wreck — tends to end up the same way, because the same six things pay.

None of those six is a family trait. Each is a solution to cover, and cover is everywhere — so the solution is everywhere too.

The tree

Drawn to the current consensus on bony-fish relationships, with families as the ends of the branches. Every branch carries its own photograph, fitted rather than cropped, so the whole fish is there to compare. Click any name to read what it is. Branches split left to right, so a fish is related to another only where their lines meet.

salt water fresh water crosses between

Pick any name — the branch on the left, or a family at the end of it.

Pick any group to shade where it lives.

Approximate on purpose. These shapes come from what the literature says about each family — “worldwide, warm seas”, “Australia and New Guinea” — and not from occurrence records, so they answer which ocean and which continent and nothing finer. A precise-looking outline around an imprecise fact would be a lie told in a hundred coordinates. The coastline is Natural Earth 1:110m, which is public domain, drawn on an equirectangular projection — which is why the far north is stretched.

Every one of them

One card for each fish named in the tree — so a label that names two fishes, like barramundi and Nile perch, gets a card for each rather than one picture standing in for both. Each card is titled with the name people actually use, carries the scientific name beneath it, and shows on its own small map where that fish lives. Click any of them to find it in the tree and read what it is. Every picture comes from Wikimedia Commons with its own credit and licence, and the photograph is of the species named underneath it.

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The honest limit: a family is a group, and one photograph cannot stand for two hundred species. Each picture is one named member of the family, saying what that member looks like — the family's full range is wider than any single fish.

Why no card carries a world population or a world total mass: nobody has counted one. The IUCN Red List keeps a field for the number of mature individuals and leaves it empty for these fishes — the Atlantic salmon's global assessment, the Nile tilapia's and the red lionfish's all do — and no one has ever weighed a species. What is published, and what the cards show, is how much is caught and farmed each year and which way the population is moving. Where a figure does not exist, the card says so rather than guessing.

How they got to fresh water

The sea and the river are not far apart — they meet in every estuary on Earth. A fish that spawns at the mouth of an inlet and lives up the river is already halfway through the door, and that is a living animal you can catch today, not a guess. What has to change is the plumbing: a salt-water fish drinks and pushes salt out through its gills, a fresh-water fish does the opposite. Rewire that, and a river system is an empty stage.

So it has happened again and again, on different branches, at different times — — separate crossings in the families on this page alone.

    One family on the page never crossed at all. The pacu and the piranha belong to a group that was in fresh water from the start, so their shape is a coincidence of a different kind — and it is the reason the tree reaches back past the perch-like fishes to show them.

    Counted from the tree, not asserted: a crossing is a family that lives in fresh water whose branch is otherwise marine. The number above is that list's length, and the pacu's family is the one fresh-water family deliberately not in it.

    The name is a description

    Sixteen different fishes get called a bass by somebody. Two of them are the smallmouth bass's actual relatives. The other fourteen are on other branches — and two are not perch-like fish at all.

    The word describes a build. It has been stuck onto at least eight unrelated families, which is the strongest argument on this page for ignoring it.

    And it is not only “bass”

    The same habit has been at work on perch, rockfish, snapper, bream and grouper — and every fish named below is already somewhere on this page. FishBase's own total is on each line, and it is the number that makes the point better than any of the names: the European perch is on record under 185 names, the wreckfish under 144, the giant grouper under 134. A word is a description, and a description has a home — the perch family, the rockfish family, the snapper family. The fault is using it as though it were the address.

    Questions people ask

    Is a snapper related to a smallmouth bass?

    Yes, but only distantly. Both sit inside the perch-like radiation of fishes, which holds roughly 17,000 species. Their common ancestor is far older than either family, so the resemblance is a shared body plan rather than close kinship.

    Is a peacock bass a bass?

    No. A peacock bass is a cichlid, in the same family as the tilapia and the oscar. Its branch of the tree leaves the perch-like fishes before the basses appear, so it is more closely related to a tilapia than to a smallmouth bass.

    How did marine fish get into fresh water?

    Through the estuary. A fish that spawns at sea and lives up the river is already halfway through, which is what snooks and barramundi do today. The changes needed are in the gills and the kidneys, and the crossing has happened independently in at least ten families — including the one the smallmouth bass belongs to.

    Where this comes from

    The tree is drawn to published phylogenies, and the family names, counts and habitats come from the standard catalogues. Where the literature is unsettled the page says so rather than choosing a side.

    Photographs

    Every photograph on this page is from Wikimedia Commons, under the licence shown. The attribution the licences ask for, in full:

    Fish classification is a moving target. Almost everything above the family level has been redrawn in the last twenty years, and some of it will be redrawn again — the family names are the stable part, and that is why the tree ends on them.

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    Nothing is uploaded, because there is nothing to upload — the page has no input. Questions about this policy: [email protected]. Last changed 3 October 2026.