Colossal squid
The largest recorded specimen was captured in 2007 by a New Zealand fishing boat off Antarctica. It was initially estimated to measure in length and weigh . The squid was taken back to New Zealand for scientific study. A study on the specimen later showed its actual weight was , but it only measured in total length as a result of the tentacles' shrinking "post mortem".
Beluga (sturgeon)
The largest accepted record is of a female taken in 1827 in the Volga estuary at and . Another specimen reportedly weighed and measured in length. Several other records of aged sturgeon exceed . These great sizes mark the beluga as the largest freshwater fish in the world. A few other species of sturgeon can attain great sizes but none match the maximum sizes known for the beluga, like Chinese, Pacific White, Oceanic European, Atlantic, Baikalian, and Kaluga, the latter a close cousin which can attain a maximum weight of , thus attaining the second largest known sturgeon size. It may be considered as a rival in size to the ocean sunfish among all extant bony fishes, although that passive marine giant has neither been nearly as heavily fished nor takes as long to attain great size, so more regularly attains massive weights. The beluga may be the second longest extant bony fish as well, after the giant oarfish, which is far more slender in build. The Beluga also rivals the great white shark, the Greenland shark, and the tiger shark for the title of largest actively predatory fish, with only the great white easily exceeding the beluga's maximum size. The giant belugas are much larger than the Mekong giant catfish, the arapaima or other sizable rivals for the title of largest freshwater fish. Nevertheless, some scientists still consider the Mekong giant catfish to be the largest true freshwater fish, owing to sturgeons' ability to survive in seawater and that it spends much of its life in brackish environments.