topminnow vs swordtail

topminnow and swordtail both are nouns.

Word	Noun	Adjective	Verb	Adverb
topminnow	Yes	No	No	No
swordtail	Yes	No	No	No

As nouns, topminnow and swordtail are synonyms defined as:

topminnow and swordtail: freshwater fish of Central America having a long swordlike tail; popular aquarium fish

Other synonyms of topminnow include helleri, Xyphophorus helleri.

topminnow (noun)	swordtail (noun)
small usually brightly-colored viviparous surface-feeding fishes of fresh or brackish warm waters; often used in mosquito control	freshwater fish of Central America having a long swordlike tail; popular aquarium fish
freshwater fish of Central America having a long swordlike tail; popular aquarium fish