82 Fred C. Rohde and Rudolf G. Arndt 



1 1 April almost all clusters had totally hatched, and by 18 April all had 

 hatched. 



Relatively detailed data on hatching are available for two single- 

 spawn clusters. On 7 March 1981, a pair of C. bairdi and eight eggs were 

 found under a brick and we assumed the fish were spawning. No eggs 

 were found here on 27 February. On 14 March, what we assumed to be 

 the remainder (and much larger portion) of that cluster was found nearby 

 on the brick. (Lifting of the brick on 7 March presumably interrupted 

 spawning and caused its resumption at another point.) On 22 March, 

 eggs of the group of eight contained well-developed embryos. On 26 

 March, well-developed young were still visible, with earlier-stage young 

 in the larger portion. On 29 March, the eight eggs were missing and we 

 presume they hatched. The incubation period was thus some 22 days. The 

 remainder had not hatched by 5 April. The brick with eggs and guarding 

 male were then placed in a plastic gallon jar with netting at each end to 

 allow passage of a current of water, and replaced in the stream. On 1 1 

 April, most eggs and hatchlings had decayed, but three eggs were near 

 hatching. The development period of these eggs was thus about 35 days. 

 About half the eggs of another cluster found on 7 March 1981 (not 

 present on 27 February) was hatched by 5 April, and the remainder 

 contained well-developed embryos. On 1 1 April only 10 eggs remained, 

 and on 18 April there was none. Time to hatching was some 29 to 42 

 days. 



As in the field, eggs of a cluster also hatch over a period of days in 

 the laboratory. A field-collected cluster maintained at approximately 

 field water temperatures (10° to 12° C) hatched as follows: 7-8 April, 4; 

 late 8 April, 59; 9 April, 14; evening of 9 April to mid-afternoon on 12 

 April, several; by mid-afternoon on 13 April, 4. Three eggs from another 

 cluster hatched on 8 April 1981. 



A male guards each cluster, and a male guarding a multiple-spawn 

 cluster was presumably successful in spawning with up to three females. 

 Koster (1936) stated that a successful male spawns with one or more 

 females, and Scott and Crossman (1973) noted that it is usual for more 

 than one female to deposit eggs in a male's nest. The same male stays with 

 a given cluster until the last eggs hatch. He is usually hidden under the 

 egg-deposition site, but sometimes lies with the head or body exposed. 

 Rarely a guarding male was found with a second male, and once two 

 males were hidden with a female heavy with eggs. These latter occurren- 

 ces, however, may have been sampling artifacts. 



Early in the 1981 reproductive season, from 22 February through 7 

 March, each male examined was in dark reproductive coloration. The 

 dorsum and sides were olive-drab to blackish, the head and fins blackish, 

 and the first dorsal fin edged with dull yellow and orange. The posterior 



