I don’t have any Blackberry SDs (BBSDs), and have not kept them but I would like to. My experience is largely with Metynnis spp. I have a general interest in SDs and in the origin of the Blackberries. Producers (exclusively in Asia?) and retailers seem to be secretive (producers), or uninformed (retailers) of specific pieces of information about this fish. Popular ‘understanding’ is that they are farm-produced hybrids of 2 Myleus /~Myloplus species (which specific ones is undisclosed) and that they cannot reproduce. Further, the majority of specimens I see online or in forums are specimens that “look” female (shape of anal fin, which works well to tell gender in all known Myleus and Myloplus), and almost none that “look” male.
I would like to gain additional information, and this may benefit others interested in BBSDs, regarding origin, gender appearance (or actual gender), and sexual behavior in these fish.
Regarding Origin –
If you would like to show some of your fish, that would be awesome!! (BBSD, Black Band SDs, or other dollars you would like to show.
[I thank you in advance, and apologize for the very long post, but hope some of you may be interested]
I would like to gain additional information, and this may benefit others interested in BBSDs, regarding origin, gender appearance (or actual gender), and sexual behavior in these fish.
Regarding Origin –
- Because of the small adipose fin, the original species must have been Myleus (~Myloplus) species. This makes sense, since attaining cross-genus hybrids should incur additional difficulty. Almost certainly no Metynnis were involved, since they have long adipose fins.
- Species involved? – It seems very likely (almost certain?) that ‘black-band SDs’ (“Myleus schomburgkii”) are involved, judging by the amount of black in BBSDs, and other features; in addition, at least one supplier describes online that ‘schomburgkii’ is involved. However, other Myleus show a lot of black as well. In addition, because of the very red fins of BBSDs, it is almost inescapable that at least one of the two species involved would be red-finned. Further, “M. schomburgkii” is a complex of at least 3 (or more?) taxa, very poorly understood taxonomically and including Wide bars (Blue hooks, and Regular barred-), and Thin Bar forms. The later are quite different, being smaller, having red fins (not blue/silver or clear), and remaining silver over the whole body. The two former, are similar in size but very different in appearance. Specialists have agreed that ‘schomburgkii’ is an unresolved species complex and although it is being studied, none of the most recent molecular analyses have included a good representation of 'schomburgkii’ forms. So, which of them, and with which other Myleus/Myloplus? It could also be that is a hybrid of 2 forms of 'schomburgkii’ (?).
- As stated above, most (but see one exception below) of what I see as BBSDs “look” female. It would be awesome if some owners posted images of their BBSDs so we get a better appreciation of this, or if it serves to dispel that notion as incorrect.
- After looking about as much I could, I have come up with A SINGLE INSTANCE of a “male looking” BBSD (see https://www.monsterfishkeepers.com/...-dollars-l-105-l-rockford-il-l-pickup.662073/) by 05spurky (Feb 29 2016). The post refers to “2 likely males” (out of 3 being sold). A clip below from that post shows a “male” (right) and a “female” (left). Everything else I see are “females” everywhere. A second picture (credit within the clip) is shown just for clarity of what I am talking about. Why would that be? Could it be that “male” BBSDs do occur but less commonly? On the other hand, it is FACT that males of most Myleus/Myloplus species are much less colorful than the females (particularly the anal fin), which have huge “hooks” in females (red or blue). Could it be that breeders perform artificial selection to keep only the most colorful ones? I kind of doubt this as the males are plenty colorful, even with the smaller and non-colored “hook”. By the way, the “male” BBSD in the picture does have a rather small and uncolored anal fin, consistent with this general feature in Myleus/Myloplus.
- It is frequent that some hybrids are not capable of reproduction (think about most mules). There are of course many exceptions, perhaps most famous in fish among popular cichlids. Inability to reproduce may stem from differences in chromosome numbers among hybridized species, behavioral or biochemical incompatibility, and others. In addition, breeders are often able to force things and perform in-vitro pairings among otherwise incompatible species.
- However, there is an important consequence of major incompatibility: if they can only be accomplished in vitro by mixing gametes of the two original species, that means that BBSDs can only be produced by this means. Gametes extracted from two BBSDs (“male” and “female”) should not produce fry, even in vitro. Does anybody know if that is the case?
- Do BBSDs exhibit a sexual drive as other SDs? Do they perform ‘mock pairings’ and ‘humping’ as all other SDs do when kept in groups and good conditions and with males and females present ? (even cross-species ‘mock pairings’, which are common). Have owners of BBSDs observed their fish participating in these behaviors in their tanks? Or alternatively, do BBSDs appear to lack a sexual drive, as compared to other silver dollars?
- An implication of a lack of sexual drive of BBSDs (if there is such a thing) would be that they would be easier to keep in dual gender tanks, particularly if sex ratios are skewed toward males: If one has too many males with too fewer (or single) females, the poor female would be constantly harassed and possibly result on unhealthy stress, inability (even if partial) of feeding enough, and other problems. If there is less sexual drive involved, things can become easier in the limited environment of a fish tank, even if large/largish.
If you would like to show some of your fish, that would be awesome!! (BBSD, Black Band SDs, or other dollars you would like to show.
[I thank you in advance, and apologize for the very long post, but hope some of you may be interested]
