Feebas is a shabby, old-looking, fishlike Pokémon with a light brown body covered in dark, irregular spots. It has large, deep-set eyes and big, pink lips. The tail and pectoral fins are dull blue and tattered in appearance. The dorsal fin is triangular with a hole in the middle.
Due to its poor appearance, it is largely ignored by predators, Trainers, and researchers alike. However, this hardy Pokémon is capable of eating anything and living anywhere. It is often found in oceans and weed-choked ponds, even if only a little water is available. While there are many of this Pokémon in existence, populations tend to cluster in small areas. Once found, its dull wits make it easy to capture. Feebas is a source of research due to its vitality despite it being unattractive and unpopular. There are even those who love to collect Feebas and only it, and reportedly are disappointed by its evolution into Milotic. In the anime, Prism Scales are revealed to form naturally on Feebas on occasion.
In Not So Fetching Feebas, Ruby obtained a female Feebas after she took a liking to him while he was fishing at Route 119. After protecting him from a wild Zangoose and Seviper, Ruby was forced to keep her on his team, nicknaming her Feefee. She later evolved into a Milotic in It All Ends Now VII after Ruby had declared that she was beautiful despite her looks.
Feebas shares several notable similarities to Magikarp:
Its level-up moves are exactly the same as those of Magikarp.
However, Feebas can learn several moves from TMs and HMs, hatch from an Egg with Egg Moves, and learn new moves via Move Tutors, making it slightly more useful in battle.
Feebas shares its category name with Magikarp. They are both known as the Fish Pokémon.
Feebas and Magikarp have almost identical stats. However, Feebas has a higher Attack and Special Defense, while Magikarp has a higher Special Attack and Defense. Both Attack and Defense stats for Feebas and Magikarp are reversed.
They share the largest base stat total increase of all Pokémon when they evolve: 340 (from 200 to 540).
They both change appearances drastically after evolution, evolving into serpentine, dragon-like Pokémon.
Feebas is the only Pokémon that requires a modification of its condition for it to evolve.
Since condition stats are a hidden mechanic in games in which Pokémon Contests are absent, a Feebas that has enough Beauty points will still evolve when it is leveled up. The Prism Scale, introduced in Generation V, was created due to the fact that there is no legitimate way to raise a Feebas's Beauty in the Generation V games, whereas with FireRed and LeafGreen, players could trade Feebas to Ruby, Sapphire, or Emerald, and a haircut or grooming by Daisy Oak or the haircut brothers affects Beauty in HeartGold and SoulSilver.
This also makes Feebas one of the few Pokémon that can evolve into a single stage through multiple methods in the core series. The others are:
Alolan Meowth, which evolves into Alolan Persian via friendship in Sun, Moon, Ultra Sun, and Ultra Moon; and via leveling up in Let's Go! Pikachu and Let's Go! Eevee.
The probability of finding a water tile with Feebas on Route 119 is approximately 1/73, with six possible fishing spots on 436 water tiles. In Mt. Coronet, it is 1/132, with four possible fishing spots on 528 water tiles. If the player reels in one Pokémon in every tile, the chance of passing every Feebas tile without reeling in a single Feebas is 1/64 on Route 119, while in Mt. Coronet it is 1/16.
Feebas has the lowest maximum performance of any Pokémon, only capable of reaching 11 stars.
Feebas seems to be based on a bass, possibly the largemouth bass. It also resembles the marine hatchetfish. Its drastic transformation when evolving into Milotic may be inspired by the classic fairy tale The Ugly Duckling, where a small and feeble duckling is treated as an outcast by other animals until it eventually grows up to be a beautiful swan.
Feebas may be a combination of feeble (weak) and bass. It also sounds similar to phoebus (Latin for shining one), possibly alluding to its evolved form.
Hinbass may be a combination of 貧 hin (poor) and bass.