Fish Species Starting with X
Browse all aquarium fish species with scientific names beginning with "X". Each profile includes care requirements, water parameters, tank size recommendations, and compatibility information for freshwater, marine, and brackish species.
The letter 'X' features a handful of intriguing species that can enhance any freshwater aquarium. The vibrant Green Swordtail (Xiphophorus hellerii) is a notable entry, alongside the lesser-known San Marcos redtail splitfin (Xenotoca doadrioi). These species are popular among hobbyists for their unique colors and compatibility in community tanks.
4 species found
San Marcos redtail splitfin
Xenotoca doadrioi
This is a little Mexican goodeid livebearer where the males do that awesome "blue body + orange/red tail" thing when they color up. They're super active, always grazing and pecking at surfaces, and they really appreciate cooler, clean, well-oxygenated water compared to your typical tropical livebearers.
Green Swordtail
Xiphophorus hellerii
Swordtails are busy, always-on-the-move livebearers, and the males' "sword" tail extension is the whole show-lots of displaying and posturing in the open water. They're tough as nails in hard, slightly alkaline water, but in tight tanks the males will absolutely bicker and chase each other around.
Green Swordtail (Swordtail)
Xiphophorus hellerii
This is the classic livebearer swordtail-the males grow that long tail "sword" and spend half their day showing off and chasing each other around. They're super active, always grazing and cruising, and they'll absolutely fill your tank with babies if you keep males and females together. Give them room to swim, hard-ish water, and some plants for cover and they're basically in their happy place.
Southern platyfish
Xiphophorus maculatus
This is the classic platy-the little livebearer that's been bred into a ridiculous number of colors, but the wild-type is more of an olive-brown fish with dark blotches. They're super active, always cruising for snacks, and you'll see fun social behavior when you keep them in a small group. Also: if you mix males and females, you'll almost certainly end up with fry-these guys don't waste any time.