Sustrate Spawners II: Killifish Mops and Peat

Introduction Our last group of spawners use some unusual techiques to reproduce. Mop spawners and peat spawners rely on heavy substrate to protect eggs, keep temperature correct and provide suitable water quality. Killifish our our number one group here, although Cory’s are popular too.

Mop Spawners General Mainly comprised of Killifish, these fish lay their eggs in mops made of synthetic yarn, or in plants. The goal seams to be to hide the eggs. Included in this group Aphyosemion Aplocheilus Epiplatys Rivukus Simposonichthys Aphyosemion amieti

How are they special? What makes these fish different from the egg lay scatterers is that their eggs are harder and larger, and fecudity is reduced to a day. Corydoras catfish also seem to fit in this group in method, although they lay many more eggs. Typically, they will attach their eggs to anything in the tank including the mop.

Tank Setup: Cory’s Hang several mops, add a sponge filter and a heater if needed. Add a pair of fish. The female will lay the eggs deep in the mop or the plant/male fertilizes them. Corydoras sterbai

Careful! Sometimes they will turn right around and eat them. Another difference with Corydoras is that the female may take sperm into her mouth and fertilizes the eggs which she is clutching in her pectoral fins, while sticking it on the preferred surface! How sneaky!

Care is Essential You must pick the eggs out of the mop daily. Place them into a small container with “anti-fungals” added (methylene blue or acriflavin). Store the eggs in a darker place (warmth doesn’t hurt.) They will incubate for days for killies and 7-10 days for rainbows. Fry can be transferred upon hatching. JAVA moss for hiding places. Most “mop” fry eat artemia first…

Peat Spawners

Introduction This group is made up entirely of Killifish. Cynolebias, Pterolebias, Nothobranchus and Fundulopanchax. These are the fish we hear referred to "true annual" killies. Cynolebias nigripinnis

How it works In the wild, they have adapted to life in correlation with the rainy seasons. They hatch, grow and spawn before the next dry season comes along, during which their watery world as they know it dries up and they die. The eggs are able to survive in this drying period (months, or sometimes years.) When the next rainy season comes along: life anew.

Tank Setup Set up a 5 gallon tank for a trio of fish. In it should be a bowl that contains about 2" of peat moss. Available at most home centers. Sometimes a bubbling sponge filter and some plants or a mop for the female to hide in will help.

Spawning Action Feed the fish well, but away from the spawning container. The male will display himself above the peat moss. When the female is interested in spawning she will approach male. They will enter peat, she lays a few eggs and he fertilizes them. (This continues several times a daily for many days.)

Spawning continued Fresh peat is needed about once per week. The old peat is gently squeezed and placed into some newspaper, lightly covered with a plastic bag overnight. The dried peat is stored in a zipped sandwich bag, in a dark place at a correct temperature.

How Long to Wait? Check the charts in the killifish books for temperature and drying /incubation time. (It’s species specific.) It can take weeks, or months, maybe years… Incorrect temperatures can cause poorly developed fry or low hatching rates.

At Last… When it is time to hatch the fry, the parents are most likely dead. (Bummer!) Wet the peat, then submerge it in a couple inches of water in a plastic shoe box. Cover lightly to shade the eggs. With in a few hours, fry can be seen popping up over the layer of peat.

Are we done? Remove them with a pipette and put into another shoebox with a few inches of water and some peat moss or a floating plant. After about 24 hours, the peat can be re-dried for another two weeks. Try to hatch more fry. This can be repeated 1-2 more times. Feed fry often and well. Because these fish live such short lives, they grow quickly.