Observations on Pronothobranchius seymouri: A Study in Thermal Precision
The cultivation of Pronothobranchius seymouri in the aquarium demands exactitude. My investigations reveal that a temperature range of 80–82°F is not merely preferable but essential for the successful incubation of its eggs and the vigor of its fry. This is no trivial detail; it is the cornerstone of reliable breeding, a fact substantiated by my own rearing of three generations from the 2019 WAC collection. Errors in prior reports, such as those fixated on the 1970s, stem from neglecting this thermal parameter.
Methodology and Findings
Consider the conditions: soft acidic water, live blackworms as sustenance, and a five-month egg storage period in a quart of moist peat-coir mixture—maintained at 82°F. These yield consistent hatches, albeit modest at 25 fry per clutch, with balanced sex ratios when raised in tanks of 10–30 gallons. Aggression, often cited as a barrier, diminishes markedly in such volumes. This is a systematic approach, not a haphazard one, and it refutes the outdated notion that small tanks suffice for killifish.
Conclusion
The decline of seymouri in the United States reflects not its inherent difficulty but a failure to apply these principles. Its persistence in Spain and Bulgaria underscores their utility. Precision in temperature and tank size is the key—nothing less will do.
A wonderful issue of JAKA, especially if you like Pupfishes. I have to take issue with Charlie's presentation of Pronothobranchius seymouri breeding in the hobby. For some reason Charlie only looked into the early 1970's breeding of seymouri based on the first 2-4 limited importations of the species. This gives a faulty impression of what is known about seymouri in 2025.
David Blair, a Scotsman in Ghana sent the first living seymouri, then known as Aphyosemion BKA-U1 to the BKA in 1968-69. They arrived in horrible condition and diseased. Few survived. Blair sent at least 1 more additional shipment to the BKA and maybe one to the AKA. He also sent fish to Erhard Roloff. These second shipments were bred to a limited degree. Ian Sainthouse maintained this collection for decades in the UK. The East Germans had some success as an East German aquarist sent Fred Stewart in Detroit eggs in 1974. (Fred showed me the eggs at that time.) Rosario LaCorte had success with these seymouri but did not continue breeding them for some reason. Like with the original Notho. fruzeri collection around this same time, seymouri eggs seemed to have very variable incubation times and this made breeding difficult for most keepers.
This initial seymouri importation disappeared in the US hobby by the early 70's, stayed a bit longer in Germany and was kept going in the UK in limited numbers by Sainthouse rather secretly. It seems this fish was not re-imported again into Europe until the 1990's and again disappeared but not without breeding advancements. A Dutch or German breeder penned an excellent article on seymouri in TFH in the late 90's and revealed a secret for success. The fish and eggs needed warmth. Ghana is hot and these fish are from open air swamps. Fish and eggs needed 80-82F temperatures. Under those conditions breeding success became more assured but not easy. The same was discovered for Gnatholebias, Terrantos and several Brazilian annuals. Success came with heat. These are not forest Aphyosemions! The fish were not so difficult. The aquarium conditions were wrong.
In the 2000's various collections of seymouri were imported. The most successful breeding wise was the WAC collection of 2019(?). I received eggs of that collection and raised 3 generations of seymouri before losing them due to over convidence and letting life get away from me. Hatches were not huge - 25 fry. Obviously many eggs died in storage but the fry were easily raised with balanced sex ratios. The trick was blackworms, soft acid water, 82F for fish and eggs and 5 month storage time in a large amount (quart) of moist, but easily fuffable peat/coir mix. Seymouri is said to be aggressive but I use large tanks for breeding - 10's -30's - and most aggressive killies are not so bad in large tanks. The idea that tiny tanks are great for long term quality breeding and maintanence of killies is nonsense. Same with raising fry. The great Brazilian killie breeder Edison Lopes discovered that raising fry in 30+ gallon ranks helped insure good sex ratios.
So a lot is known about seymouri today. It is very short lived so it must be bred and needs great food to live its fast life well. I think its gone again in the US today. Paco Casado still has it in Spain and Kiril in Bulgaria has bred it for years. But most annuals are gone in the US today. From a sought after family of fish in the 60's-80's, annuals are largely ignored today. They were once the elite of fish. Today its plecos, corys, gobies, shrimp and ricefish!
