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FAQs on Scats, Family Scatophagidae, Identification

Related Articles: Scats, Scats and monos; Old favourites and new species for the brackish water aquarium by Neale Monks,

Related FAQs: Scats 1, Scats 2, Scat Behavior, Scat Compatibility, Scat Selection, Scat Systems, Scat Feeding, Scat Disease, Scat Reproduction,

Selenotoca identification help     1/3/17
Good day,
<Morning, Joel!>
A friend showed me a picture she took at a LFS some time back and what caught my eye was a marine tank which included Monodactylus spp. and Selenotoca spp. alongside damsels and other assorted marine fish.
I originally identified the scat as the more common Silver Scat (S. multifasciata) but I've never seen one at that size with so few bands and spots. Is it possible that this was a Moon Scat (S. papuensis)? I've read elsewhere on WWM that size of spots is the defining characteristic, vice number of spots, and the smaller size supports my original identification. Google has offered no help with pictures for S. papuensis. I would greatly appreciate your thoughts on this subject. Sorry for the blurry picture, hopefully it is clear enough to make an educated guess.
<It is indeed.>
Thank you again,
<Probably Selenotoca multifasciata. I've yet to see convincing Selenotoca papuensis in the aquarium trade. Some authorities maintain they are the same fish. Hard to know for sure. Variations in spots and stripes are common among Selenotoca multifasciata, making visual inspection an unreliable (probably useless) way to tell the two species of Selenotoca apart. Frustratingly, while scientific references (and Aqualog) refer to the key difference between the two species being the number of dorsal fin spines, nothing available freely online actually says what this difference is! Nor does my Aqualog book. Fishbase is useless on this species, too. So for now, I'm stuck with using Sterba's 'Freshwater Fishes of the World'.
His drawings of the two Selenotoca species shows them nearly identical in appearance, except that the bands and spots are much thicker and bolder, more like Tiger Barb markings than a typical Silver Scat. With all this said, your specimen is certainly unusual, I simply feel that it's within the range of variation among Selenotoca multifasciata. Sorry I can't be
more certain or helpful; Maurice Kottelat is really the chap you want to get in touch with. Cheers, Neale.>

Fish Identification 8/3/11
Hi guys!
<And gals...>
I'm asking a question for the first time but have learned tonnes from WWM. Thanks for that! I have a well established 80 gallon marine tank thanks to you!
Can you please help me identify the fish in the attachment? My LFS said it was a Silver Cod then I thought it must be a grouper since they swim together but Googled a lot but no luck.
Thanks! :D
<This/these are Selenotoca multifasciata. Bob Fenner>

Scatophagus species Hi, I caught a school of scats in a mouth of a freshwater stream in Bintan Island, Indonesia. They have an orange base and broad black stripes. They change colour constantly, so that they sometimes become totally black except for the orange at the top. What specie of scat do you figure this to be. /JJ <I'll be... have never seen the species but it does sound like Scatophagus tetracanthus. Please see the description here: http://www.wetwebmedia.com/Scatart.htm or plug the name into your search engines or fishbase.org. Bob Fenner>

Re: Scatophagus species Dear Bob, Thanks. I found a picture of the tetracanthus at http://www.ohiexchange.com/armke/images/scatophagus_tetracanthus.jpg <Ah yes> I think I may have juveniles (1 inch) of this specie. There is a hint of the orange at the dorsal edge of the scats in the picture. Perhaps the orange disappears as the scat mature. <Yes, unfortunately> Indeed when I made a closer examination of what I have, I notice that interspersing the vertical band is not quite orange but yellow-tint silver. Maybe I'll send a picture when I can borrow w a digital camera. /JJ <Very good. Will post. Bob Fenner>

Re: Scatophagus species Dear Bob, As promise I am attaching a photo... <Very nice> This is not a very good photo as the camera ran out of battery before we could get a good shot. Nevertheless you can get an idea from it. I had wanted to get a picture of the scats when they turn completely black except for the orange on the dorsal edge, but that will have to wait. <Have seen this... esp. on S. argus (here), when "bummed"... due to water quality, nutrition, social issues> Also, now that the scats have grown a little larger, I am also beginning to doubt of they are tetracanthus! The stripes are not as broad, and in fact the older ones are beginning to have spots appearing (though I know they are not argus because I caught juvenile arguses before). <This is assuredly argus> Would be glad for identification. /JJ
<Bob Fenner, just back from Hawai'i>

Re: Scatophagus species Hmm... I found a photo in LiveAquaria.com which has Ruby Scats as Scatophagus Argus, the picture of the scat does resemble what I have. But I once caught green spotted scats which I assumed to be the Argus. Do Argus juveniles have different appearances? I'm a little confused. <Mmm, please see here: http://www.wetwebmedia.com/Scatart.htm These are the same species. Bob Fenner> /JJ
Help with Identification -- 10/09/07 Hello Crew, First I would like to thank you guys for providing us novices with a great deal of help and advice. I'm learning all the time. <Hello, and thanks for the nice words.> I recently moved into a house in Thailand and inherited a reef tank which was left by the previous occupant (who left in a rush to Germany apparently). The landlord informed me that the tank had been left untouched for a couple of weeks and has given it to me. When I turned the power on I was shocked to see that all of the occupants were still alive (skinny but alive) including a few nice corals (red leather finger, daisy polyps and star polyps). After spending most of the past couple weeks on your site and goggle images I have managed to identify most of the live critters I have to 3" tang, royal Gramma, 2 2" false percula clown fish, 4" lawnmower blenny, 2" yellow watchman goby, 1 coral brand shrimp, 1 skunk shrimp, 6 blue leg hermit and 3 turbo snails. I would be very great full if you could help identify the attached fish. I have two in the tank, I have searched but have been unable to find anything close. They're small, copper with black spots and very very quick swimmers. <Picture too small, but they look like Scatophagus species of some sort. The body shape and the distribution of the fins looks about right. Scatophagus are euryhaline marine fish that swim in and out of freshwater rivers throughout their life. They are extremely hardy. Basically omnivorous. Not sure they're typically classed as "reef safe" fishes, since they'll eat anything they can cram into their mouths, but they won't harm sessile invertebrates or armoured things like snails and shrimps.> Since I made a water change, something as appeared on the glass in 2 places. It looks like they could be eggs of some kind?? (see attached photo) There are small rows of white dots, similar in shape to a finger print. Could you possibly identify these?? good or bad?? <Too small for me to identify. Need a bigger picture. Aim for a photo around 600 pixels across.> The tank is 75 gallons, wet/dry filter, 4 pumps, protein skimmer (unknown, no brand or labels), lots of live rock, 1.5" crushed coral substrate, Salinity is 1.05, ph is 8.4, temp 79-81 degrees, nitrate >10, NHO3 =0, 150 watt metal halide lighting with 20,000k light. <SG is 1.05? That can't be right. Do you mean SG 1.025?> Sorry for the length of this email, I hope I've not bored you to sleep! <Nope. Thanks for writing.> Any advice is greatly appreciated Thanks Tony

Re: Help with Identification -- 10/09/07 Thank you for the quick response, I've attached another photo, the round white dots are very small and its difficult to pick up on the photo. If you can't identify it would it be better to just remove them? Better safe than sorry?? Just one more question, with a 75 gallon tank how much daily water evaporation would you expect, it seems I have to top up around half a liter a day is this normal? Thanks again P.S. Yes the salt is 1.025 !! <Hmm... very interesting. The pattern is odd, and reminds me more of fish eggs than, say, snail eggs. Snails tend to deposit their eggs in masses well after each partner has fertilised the other (snails being, largely, hermaphrodites); but fish lay them in rows, because they glide along the flat surface, the male following the female fertilising them. So I'd be tempted to leave them in place and see what happens. You could try and roll them off the glass into a floating breeding trap or something, if you were really worried. That works with some fish eggs quite well. If they are fish eggs, they should obviously have a developing embryo inside them. I may be barking completely up the wrong tree here of course, in which someone else at WWM will see the photos and tell us what they might be. There's no "normal" rate of evaporation: it depends on air movement, air temperature, air pressure, ambient humidity, movement of the water, and all sorts of other factors. In other words, "it is what it is" and all you can do is top up the water loss each day (or however often you do it). Were the two little fish Scats? Cheers, Neale>

Re: Help with Identification -- 10/09/07 Thank you again Neale, The two fish were indeed scats, of the spotted variety.... was just reading up on them it seems they're a much more popular fresh water fish than marine fish which I guess is why I couldn't find any info on them as I was looking in the wrong place! <They are really only temporary residents in freshwater, and ironically do much better in marine tanks than freshwater ones, despite being sold as freshwater fish. Enjoy they; they're lovely fish, and so long as they get lots of bulky plant foods, they'll be happy. Basically treat like a tang.> As for the maybe fish eggs, being a bit of a pessimist I was a little worried that they may be parasites of some kind as I could find nothing similar on the web. <Unlikely to be parasites. Parasites don't leave their eggs in the open (you've been watching too much 'Alien'!). Parasites tend to put their eggs inside something a host will eat, such as a smaller prey animal. So you can basically write off the idea these are parasites.> I will keep a look out on your site to see if anybody can identify them. I will leave them where they are for now and see what happens. <Indeed.> Thanks for your time, let me know if you ever come to Bangkok and I will buy you a beer :) <Hah!>
Kind regards
<Cheers, Neale>

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