Blenny article

[NicoleC]

Thanks for the recent article on blennies. I was surprised to learn that my female bi-color is probably a male. Although I don't have more than one to compare sex traits like the fins, "she" is probably near to 70mm long, and the growth once placed in captivity was explosive. He appears to be fully grown now. (Although I could swear she, er "he," has more teeth than any other fish except a piranha.)

Now to my question: You stated in the article that bi-colors are obligate microalgae eaters. Although mine eagerly ate algae off the back of the tank at first, she rapidly adopted the mostly meat-based food the clowns and gobies eat. She refuses nori or algae-based foods like Formula 2. Except for a bit of hard green algae on the glass and a bit of cyano in one spot on the sand bed, I don't have any micro algae for him to eat. I have not been able to cultivate algae on the back glass, and starting an algae tank hasn't worked either -- and since he so eagerly eats the other food and is plump and healthy looking, I guess I stopped worrying about it.

I do have several species of macro in the tank, which he ignores, except for recently there have been what appear to be bite marks on the halimeda. There's only one fish crazy enough to try it. Yuck... there are much tastier macros in the tank!

Do you think that the blenny's choice of diet is detrimental to his long-term health? I was considering pairing my bi-color up, but I want to be sure I have the food situation resolved first. If I get that far, your comments in the article on the difference in appearance between sexes will be very helpful.

If necessary, I could attempt different brands and formulations of algae-based food to find something he may find more palitable. If fish food doesn't work, I have access to many different kinds of dried seaweed species between the local health food stores and asian markets.

 

[Sloeber]

hi nicole,

i think you'll be fine with the blenny eating whatever it can. in the wild it may eat only algae, but once in an aquarium all bets are off. let's not forget that a large part of the diet of mysis and brine is micro algae, too.

caulerpas, halimeda, etc., fall under the category of macro algaes and it is not likely the blenny will consume much of those. as you alluded to, they would rather scrape the tough stuff from the glass or rocks instead of consume macros. honestly, i bet the blenny is sraping the rocks or glass more than you notice, too.

anyway, if the fish is eating weel and is plump, i think you are doing somethign right and should be OK to try and pair them up!

HTH

henry

 

[NicoleC]

Thanks for the reply. Hopefully his diet is good -- he does seem slimmer lately, but he was pretty fat for a while and I think his current condition is more appropriate. It's now more like the photo above, which was taken when he was still growing out.

I actually have been trying a lot of foods for him lately. He HAS been chowing on the halimeda -- the bites marks are almost cartoonish! I have been placing fresh seaweed in a clip in the same spot he's been eating the halimeda, but so far only the snails are being attracted... in herds.

After spitting it out a lot, he seems to be getting a taste for Formula 1 flake. Good, says I; it's a healthy addition for the other fish, too, and none of them are picky eaters at all. The different foods has certainly piqued his interest and he seems to be enjoying the variety. The other fish are not the gourmands he is; they eat anything.

By the way, the more I look at my blenny the more I think "he" has the characteristics of a female, despite the large size. I was able to see about half a dozen young bi-colors at an importer this weekend, and they all seem to have a more pronounced dorsal fin -- although they were much smaller and less developed, so it was hard to compare. I also don't see anything resembling "thick fleshy tips" on the anal rays. He does, however, have pronouced white markings when camoflaging, similar to those reported as a mating coloration of males.

Was my original guess correct, and she is a female despite her size? Given her/his high protein diet and predator-less environment, I suppose size could be a poor gauge. Is there enough detail in the above photo of the dorsal and caudal fins to make a sex ID?

Thanks,
Nicole

 

[Sloeber]

I actually have been trying a lot of foods for him lately. He HAS been chowing on the halimeda -- the bites marks are almost cartoonish!

we love pictures in this forum! :lol:

I have been placing fresh seaweed in a clip in the same spot he's been eating the halimeda, but so far only the snails are being attracted... in herds.

LOL. do any fish eat it? ...it may learn from othe fish. once they begin to feed from the dried algea they will usually attack it aggressively.

After spitting it out a lot, he seems to be getting a taste for Formula 1 flake. Good, says I; it's a healthy addition for the other fish, too, and none of them are picky eaters at all.

i mix up the variety of my foods regularly, but i generally feed formula 1 flake everyday.

Was my original guess correct, and she is a female despite her size? Given her/his high protein diet and predator-less environment, I suppose size could be a poor gauge. Is there enough detail in the above photo of the dorsal and caudal fins to make a sex ID?

it be hard for me to be able to see that unless you were a professional photographer :lol:

are you able to count the number of dorsal fin rays and anal fin rays? is asking it to smile so you can count teeth asking too much?

HTH

henry

 

[NicoleC]

The good news is s/he has stopped eating the halimeda. S/he hasn't touched the nori or wakamai as far as I have seen -- the fish tastes everything that goes in the tank, so I'm hard-pressed to think it wouldn't at least TRY the seaweed! I have no other grazers that might care to eat it. I'll keep putting it in there.

I will see what i can do about a sharp pic of the fins. The pic above isn't very sharp, but I thought it showed the overall fish better. If all else fails, there is always the local reef keeping buddy that IS a pro photographer Hope the teeth aren't a requirement, though. If it is, next time she bites the snot out of me I'll take a pic of the wound!

 

[NicoleC]

No luck on the fin pics yet (although I count 14 spines on the caudal fin), but here's a pic of those bite marks. I even caught her in the act. As a bonus, she also took a bite of the wakami in the clip (to the right), so hopefully she will get the idea:

FWIW, I count 11 spines on the anterior dorsal fin -- I don't know if you need both or if they would actually count as a single fin since they are attached. Actually, counting again, it might be 12...

 

[NicoleC]

RIP Buddy the Blenny

She jumped right through the eggcrate today. I remain convinced she was looking for a mate, since she's been unhappy since the gobies paired up and got worse when they started spawning.

I didn't have the heart to count fins, even if she finally did hold still.

 

[Sloeber]

hi nicole,

sorry to hear about the most recent developments. having seemingly healthy fish jump from our tanks may be the most hurtful way to lose a fish.

FWIW (probably not much now), if your counts were accurate, it sounds like you had a juvenile fish.

HTH

henry

 

[NicoleC]

Sorry to revive an old thread. I couldn't resist and got another bicolor, who, like her predecessor, has grown rapidly. This one eats Formula 2 flake almost exclusively and fortunately has shown no interest in UP!

She also poses for better fin-counting pics. Do you know the specific ray counts to determine sex? FishBase says: Dorsal spines (total): 11-12; Dorsal soft rays (total): 15-18; Anal spines: 2; Anal soft rays: 17-21, but doesn't specify where in that range the sexes might lie.

Secondly, do you know of a source for a description of egg laying appearance and behavior? Well, at least ones a layman without access to a good marine science laboratory is likely to be able to get hold of? Would Threser's "Reproduction in Reef Fishes" be useful?

I can't resist a pic of Buddy II. Now if only I could get both ends of the fish to fit into a macro focus.

 

[Sloeber]

Sorry to revive an old thread. I couldn't resist and got another bicolor, who, like her predecessor, has grown rapidly. This one eats Formula 2 flake almost exclusively and fortunately has shown no interest in UP!

She also poses for better fin-counting pics. Do you know the specific ray counts to determine sex? FishBase says: Dorsal spines (total): 11-12; Dorsal soft rays (total): 15-18; Anal spines: 2; Anal soft rays: 17-21, but doesn't specify where in that range the sexes might lie.

determining sex gets a lot more confusing than checking the count of rays, but it does help... are you able to give me the data? there are a lot of factors that come into play which makes it near impossible for me to report the type of info you are asking.

on average, the males will have a higher total average of dorsal and anal rays and caudal vertebrae than will the females (for bicolors only, not other species). females will average around 60 of the combined features whereas the males will have about 77 or 78. remember, this includes the caudal vertebrae, something you cannot account for. FWIW, they usually account for 23 - 25.

can you tell me if the fifth dorsal ray is any longer than the others?

what about the nasal cirri?

Secondly, do you know of a source for a description of egg laying appearance and behavior? Well, at least ones a layman without access to a good marine science laboratory is likely to be able to get hold of? Would Threser's "Reproduction in Reef Fishes" be useful?

geez, i don't know. i do not own such a book and i'm not familar with the one you are asking about. perhaps try contacting todd gardner - he has been researchign breeding gobies as of late.

HTH

henry

 

[NicoleC]

I was asking about the method because she is still young and may not have developed fully yet, although she stopped growing some time ago. She is nowhere near as large as my last bi-color, and is more in line with the size I usually see -- but she is also not a carnivore like the last one!

can you tell me if the fifth dorsal ray is any longer than the others?
Not to my eyes; it looks the same as the others. There is a fleshly lobe betwee the 2nd and 3rd rays, but I have seen these on all the bi-colors I have seen.

what about the nasal cirri?
The "antenna" are orbital cirri, right? I haven't seen any other cirri. The "antenna" seem slightly longer and more delicate than my last blenny.

I will try to get good fin counts.

The book I mentioned is out of print. I asked about the eggs because I saw her with what appeared to be two streams of eggs and a visible oviposter. My first thought was parasites, but I seem to have ruled that outs since a) there hasn't been a repeat b) no other fish have been affected and c) my efforts to hatch a sample of the eggs I grabbed didn't work.

Without a mate, I guess she could produce eggs, just not know what to do with them without the mating interaction. But since they looked more like cerith eggs than anything else, it could have just been something she ate... which is the most likely scenario to me. Unfortunately, there is not much reference material out there to investigate further.

 

[NicoleC]

Not a single pic of the anal fin, and of course she isn't cooperating. I will keep trying. Judging from what you say, she'd probably have to be a female.

1st dorsal fin: 11 or 12 rays
2nd dorsal fin: 17 rays
plus caudal vertebrae: 23-26 est.
subtotal: 51-55

So the anal fin would have to have a LOT of rays to be a male, right?