Christmas tree at aquarium in Fukui Pref.
Dec. 04 FUKUI, Japan
Breeding staff wearing Santa Claus costumes set up a 3-meter-high Christmas tree in a water tank at Echizen Matsushima Aquarium in the town of Mikuni, Fukui Prefecture, on Dec. 4, 2009. Some 3,000 fish of 20 kinds swim in the tank, which measures 10 meters in width and 6 meters in depth. (Kyodo)




The Oxford Advanced Learner’s Dictionary says:
fish
noun (pl. fish or fishes) [HELP] Fish is the usual plural form. The older form, fishes, can be used to refer to different kinds of fish.


Therefore, shouldn't fish be "fishes"?

 

I don't know about anyone else, but I would never use fishes, no matter what the dictionary said.

 

The 3000 fish aren't 3000 different kinds of fish. The special plural can be illustrated by saying that trout, perch, pike are fishes. (But usually we say 'fish' anyway - 'fishes' is rare in any sense.)

 

Sigh, this is one of those subjects in which we are swimming in prior threads and there should be no need to go angling for repetitious comments, regardless of which school of thought has lured you into its embrace.

little trolling through the WRD for "fishes" reveals

fish and fishes
plural of fish, fishes?
Fish or Fishes
two fishes
State preserves of loaves and fishes
fish/fishes
fish/fishes
fish or fishes?

 

In the present example, there are 3000 fish in the tank, but 20 fishes in the tank.

 

I would probably say fishes if I could count them (probably as I am seeing them in an aquarium)--and that is as a noun. But, then again I'd also say buffaloes, elephants, and hippos, where I've noticed some native speakers drop off the s.

 

Other options:
Some 3,000 fish, of 20 different species, swim in the tank.
Among 20 different species, some 3,000 fish swim in the tank.
With 20 different species, some 3,000 fish swim in the tank.
Including 20 different species, some 3,000 fish swim in the tank.