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Blackstripe Topminnow

Fundulus notatus

Blackstripe Topminnow at the top


In the past I have been reluctant to keep and try to breed native species of fish because of their requirements.  Some eat live foods only, require cold temperatures, or are very seasonal.  I was encouraged to try some Fundulus notatus and I was glad I did!  They are peaceful, easy to breed, eat most all foods, do well at 75 degrees F., and can be bred at any time.  The Blackstripe Topminnow is a killiefish that is native to North America and is mostly found in the Mississippi River drainage of the Midwest USA, although some are found in southern Michigan.  It is a slender fish that reaches 3 inches with an upturned mouth, indicating it is a surface feeder.  It has a lifespan of about 3 years and they seem to do fine at a fairly wide range of temperatures (64-77 degrees F.).  This fish is colored brown-olive with a white lower body.  Along its’ side from the snout to tail is a black longitudinal band with somewhat jagged edges.  Females have rounder fins and less intense colors.  Fully mature males have longer anal and dorsal fins that are somewhat pointed.  Males may also have more ragged edges on the longitudinal stripe.  This fish is similar to but distinguished from Fundulus olivaceous, which has smooth edges on the stripe.  It is interesting to note that a survival mechanism of this fish is the water surface itself.  The reflection of the fish on the surface as seen from below will distract and confuse predators and allow them to escape.


Keeping and breeding this fish is quite simple.  They are surface dwellers, so give them enough space and open area on the surface.  They school, so that 4 or 5 individuals will be more content and out in the open than one or two fish.  They are expert jumpers and need to be kept covered!  I got mine to eat dry, frozen, and live foods, but they eat frozen and live foods with more gusto.  They feed mostly at the surface, but will sometimes go down and pick up foods off the clean glass bottom of a tank.  Fundulus notatus will lay their eggs in a dark colored nylon mop up by the surface, although if gravel is present, they may try to lay eggs there.  `To get them to lay eggs required very heavy and frequent feedings and they did not lay numerous eggs for me, but they were fairly large.


I picked and placed the eggs in a quart pan with tapwater and 2 drops of 5% methylene blue to retard any fungus.  Cover the pan and place a slowly bubbling airline in it to keep the water oxygenated.  At 75 degrees F., the eggs hatch in about 2 weeks.  The fry have tiny mouths and need infusoria for a few days, and then they will take newly hatched brine shrimp.  They stay and feed near the surface so a slight water movement is necessary to keep food in front of them.  If the fry are crowded, they will nip at each other, so they seem to require a certain territory.  Because the eggs are few in number and take 2 weeks to hatch, there can be size discrepancies between the fry and the smaller ones may get eaten, so some floating plants will help.  It seemed that the fry matured slowly, which I guess might take 8 months to a year.


I recommend that others keep and breed Fundulus notatus.  It is a peaceful, active, and easy to keep and breed.  It gives one experience in both killiefish and native fish species that can be used in breeding more difficult species later.