The spores are stirred up from the bottom by the inflow water. They invade the 

 newly set-out brood, especially when the broodlings are crowded at the overflow and 

 come into intimate contact with the through current. The sporozoa then migrate into 

 the most varied cartilages of the body, which they more or less destroy. In the course 

 of about 40 to 60 days with rainbow trout brood they can arrive at the cartilage adjacent 

 to the hearing and equilibrium organ, lliis causes injury to the functions of the adjacent 

 nerves: the typical rotary movements which have given the disease its name, then occur. 

 Almost at the sa;ae time rejiarkable black colorations of the tails occur for the first 

 time, later deformities, spinal column curvatures, gill cover and head shortenings, etc, 

 (see Fig. 70) occur. 7/ith brook trout, latent infections and black colorations occur 

 most frequently, and rotarj' movements occur with less frequency. 



In the autumn, about from October onward, spores develop in hardening and ossifying 

 cartilages at the infected places. With the perishing of the Infected trovitj the soil 

 fran then on becomes again sown with spores. The healed-up fingerlings and older fishes 

 are accordingly always the conveyors and distributors of the rotary disease, the germ 

 carriers, without being sick themselves any longer. For with the increasing hardening 

 of the cartilage, it is simultaneously the "feeding time", and thereby a g'Oal is set for 

 the activity of the lentospora, Natvirally a vary special danger lies in this phenomenon: 

 It is not possible for the pond manager to determine whether a purchased, seeniingly 

 healthy fish is not a spore carrier and will sow the pond bottoa with spores on perishing. 

 Schaeperclaus, who recently exhaustively investigated the disease, emphasizes, that there 

 is no panacea against the rotary disease, but that the correct application of the follow- 

 ing precautions make a successful control possible: 



(1) Avoidance of the tfiking in of fishes of every kind and size from 

 fisheries or waters with rotary disease, 



(2) Avoidance of the purchase of very far developed eggs fran managements 

 with rotary disease, 



(3) The rendering innocuous of all trout healed from rotary disease, at 

 least growing them in ponds which are in no kind of connection with 

 the brood ponds, 



(4-) Brooding of the trout in spore-free v/ater, if possible not coming 

 out of ponds. 



(5) Feeding in nursery ponds, in spore-free water during at least four 

 weeks . 



(6) Further brood growing in thoroughly calcium cyanamide (see Chapter VIII) 

 treated ponds, having the least possible through flow, 



(7) Ccmplete separation of the brood ponds from the mast ponds, feeding 

 directly out of brooks, never out of mast ponds, exclusive use for 

 brood growing. Fishing out of the brood ponds by the end of September 

 at the latest, keeping them drained until the next growing period, 



2, Worm Parasitic Diseases , 



Blood-worm Attack . The trematode worm Sanguinicola of up to 1 millimeter size 

 very frequently occur in two fonns, (S. inermis ) with carps, and (S. armata ) with tenches, 

 and especially in the onion-like appendage of the aorta at the heart. Its eggs laid in 

 the height of summer migrate with the blood into the gills and kidneys. Strong collections 

 of eggs during the tlT.e from July to autumn cause frequent diseases and all sorts of 

 secondary diseases with the carp brood. The larvae of the blood-worm bore through the 

 gills and then as free-swimming ciliated larvae they penetrate into snails (Llmnea-species), 

 Here they develop into migrating larvae, tail bearing cercaria, which in turn again seek 

 out fishes and there develop into the sex ripe worm. The destruction of the snails by 

 draining and ILiiing the ponds is therefore the most promising v/ay for the control of the 

 blood worm. 



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