Not a completely healthy one but I don't think the size is affecting this guy too much... It was obviously a healthy fish for a while until something happened to it. I wonder how old the fish is and when the OP got them...
Harlequin colours
- Thread starter Chris the fish
- Start date
Espei and one other one I can think of but I forget the name... That's shape not the coloration or style.
I have nothing more to add. You help the OP.
Just so I know, was that meant in a sarcastic way or a serious way? I sometimes am confused over just writing... And just so you know, I don't think a harlequin SHOULD look like that but some animals turn out to be smaller than normal. There are teacup pigs that can stay really small or get 600lbs... Sometimes peacock gudgeons get to 3in and other times they stay around 1in.... I think we both speak from different terms which is fine. You speak by textbook while I speak from knowledge gained from other aquarists and my own limited experience. You do have a lot of experience but because of certain things you rely more on the older textbook ways which work really well in SOME aspects, just not all the time. New things come about through years of aquatics which is why I don't put all my trust in older books but I don't trust in all online sources either. I try to find things that are relatively recent and have been proven to work... Everyone has their own way of doing things and you and I definitely have different ways of keeping aquariums and I don't think that one is wrong and the other right. I think we are both right because its just what works for us... Obviously there are the main basics but then there are a lot of the debatable things in aquarium keeping which can be done differently depending on a person's circumstances.
The little male that has lost colour is sick. His back is curved and his belly sunken. If it happened suddenly, it's disease. Age could also be a factor. But whatever snarkiness is flying around, he isn't well and his chances are small.
I doubt very much they spawned as that is an inhospitable habitat for a member of the Rasbora group. That species spawns on the underside of Crypt or sword leaves, and that tank is set up with a plantless marine decor - not for tiny rainforest fish. Mine would always engage in fantastic courtship dances with electrified colours as part of their egg laying ritual.
@Rocky998 - the all things are relative way of looking at things doesn't work with fish species. There's a wealth of knowledge built up from people like you and me, earlier aquarists and scientific researchers who have looked at and studied fish for generations. They aren't all still with us, but their knowledge carries on through the textbooks into the digital age. You can find minor errors in old texts, but in general, they are good. What has changed is our understanding of evolution as DNA has become such a wonderful tool. There has been a lot of renaming as we've discovered how the puzzle of life fits together, and that's to be expected. Science isn't the truth, or a rigid system, it's the process by which we work with others to try to understand. Along the way, we've found a lot of truths and facts, but it's still a work in progress and always will be. Don't trust any book written before about 1850 - but from then on in, give them thought.
After that - the fish in the OP's photo looks bad,but they can linger on like that for some time.
I doubt very much they spawned as that is an inhospitable habitat for a member of the Rasbora group. That species spawns on the underside of Crypt or sword leaves, and that tank is set up with a plantless marine decor - not for tiny rainforest fish. Mine would always engage in fantastic courtship dances with electrified colours as part of their egg laying ritual.
@Rocky998 - the all things are relative way of looking at things doesn't work with fish species. There's a wealth of knowledge built up from people like you and me, earlier aquarists and scientific researchers who have looked at and studied fish for generations. They aren't all still with us, but their knowledge carries on through the textbooks into the digital age. You can find minor errors in old texts, but in general, they are good. What has changed is our understanding of evolution as DNA has become such a wonderful tool. There has been a lot of renaming as we've discovered how the puzzle of life fits together, and that's to be expected. Science isn't the truth, or a rigid system, it's the process by which we work with others to try to understand. Along the way, we've found a lot of truths and facts, but it's still a work in progress and always will be. Don't trust any book written before about 1850 - but from then on in, give them thought.
After that - the fish in the OP's photo looks bad,but they can linger on like that for some time.
After reviewing the photo multiple times trying to find something wrong other than size and color... I cant see any wrong curvature on the back or a sunken belly. To me it's a fish that was just born smaller. The curve on its back probably looks like a deformation because it was born smaller, so the curve may look wrong on the fish when in reality its just the normal "hump" on harlequins. All harlequins have a "hump" like thing on their back that makes them look go circlish.... That one just happens to be small. But the thing I am concerned about is it discoloring overnight... That is a sign that its sick or unwell in someway. But I dont know what it could be... We would have to ask for water parameters and such...
And yes I know that the old textbooks are good. But some info IS outdated which is why I check it with multiple sources... As with anything I read online or on paper... There is a lot of good information in older books but it can't be held up as the almighty source of information either and that goes for anything scientific.
@Rocky998 There's a trick the 85 year old fish guy who ran the store I used to hang around in when I was a teenager taught me. Look at the base of the gills on a fish that doesn't look "right". If there is an indentation there (as there is in the photo) the fish is diseased. If the indentation is followed by a flat stomach, and the fish has an almost loachlike appearance, with a high back (in a species that doesn't generally have that shape), there are often internal cysts or parasites.
He's smaller because he's male, and the others pictured are female. It isn't his size that's the issue. He's hunching in, and on his way to a hollow body - both signs of physical problems internally.
All male Trigonostigma (they used to be Rasbora) are smaller and thinner than the females, but he's crossed a line, sadly.
That kind of backs you into a corner as far as getting researched information goes. There are no almighty sources, for sure, but there is a process of learning you can participate in. I've had fish for 55 years, and the only major changes I've seen are an improved understanding of fish evolution and its implications, some better technology and a stronger understanding of how water works and what it is. They look big, but if you read the Innes books from the 1940s, the basic fishkeeping info is still sound. The focus has shifted, and so has the science, but for info on putting a fish in a tank and having it thrive, the good sources hold steady. It's a lot of fun to see how what we know expands, but how we keep fish isn't rocket science.
He's smaller because he's male, and the others pictured are female. It isn't his size that's the issue. He's hunching in, and on his way to a hollow body - both signs of physical problems internally.
All male Trigonostigma (they used to be Rasbora) are smaller and thinner than the females, but he's crossed a line, sadly.
That kind of backs you into a corner as far as getting researched information goes. There are no almighty sources, for sure, but there is a process of learning you can participate in. I've had fish for 55 years, and the only major changes I've seen are an improved understanding of fish evolution and its implications, some better technology and a stronger understanding of how water works and what it is. They look big, but if you read the Innes books from the 1940s, the basic fishkeeping info is still sound. The focus has shifted, and so has the science, but for info on putting a fish in a tank and having it thrive, the good sources hold steady. It's a lot of fun to see how what we know expands, but how we keep fish isn't rocket science.
Thats some good information at the top there! Very useful to know!
And I can agree with the bottom portion of what you posted. Again, I'm nit saying that older books are not useful. They definitely have a TON of very useful information but SOME can be outdated and have wrong under researched information
HI and welcome to TFF... 
Fish can change color (fading or getting more intense) by their mood they're in.
Fish can change color (fading or getting more intense) by their mood they're in.
Chris the fish
New Member
I changed the lights to white and in a couple if days he has gone back to the original colour so maybe it was the red and blue lighting? I have had the lights that way for a few weeks though but anyway he looks fine and healthy again 
Thats great to hear!!I changed the lights to white and in a couple if days he has gone back to the original colour so maybe it was the red and blue lighting? I have had the lights that way for a few weeks though but anyway he looks fine and healthy again
Beastije
Fish Addict
Hi, as someone who has been watching my 5 year old harlequins go through all sort of changes in their life age, let me just put in here:
water too cold or too sudden change in temperature = loss of color
fish stressed or sick = loss of color
old age and dying = narrower, prolonged, loss of color, twitchy swimming
on the other hand had one which was more white than the others for 6 months, he was ok after a while, might have been internal problem.
They will appreciate a bump of frozen food or live food to get back to normal quicker.
Not sure how many of them do you have, they will spawn after a water change and a good feeding, but they also like to eat the eggs immediately, so it looks like a big cannibalistic frenzy.
water too cold or too sudden change in temperature = loss of color
fish stressed or sick = loss of color
old age and dying = narrower, prolonged, loss of color, twitchy swimming
on the other hand had one which was more white than the others for 6 months, he was ok after a while, might have been internal problem.
They will appreciate a bump of frozen food or live food to get back to normal quicker.
Not sure how many of them do you have, they will spawn after a water change and a good feeding, but they also like to eat the eggs immediately, so it looks like a big cannibalistic frenzy.
You have lots of experience with Harlequins, is the fish in question a healthy fish in your opinion?
Beastije
Fish Addict
Males (which have a red eyes in older age and the black stripe leads all the way down to the stomach) tend to be leaner and longer and if there was a stress of some sort, it could have lost the color.
Feed with some quality food, do more often water changes for a week or two to ensure your water quality is not poor, investigate if there are no causes for the poor water quality ( rotting plants, dead fish/snail) and you will see.
If the fish swimming ok, not twitching and not "staying behind" in the current, it is not old yet and can get better, unless it is some disease we have not yet identified. The round ones actually look a bit fat to me, could be they are full of eggs or overfed, if the female has eggs it can look like it has a bump on the bottom of the belly, that was my experience.
With the light you had, you are missing on their hues. In a cold white light you can see bluish or purple hues in their side. And the amazing red tips of their fins !
Feed with some quality food, do more often water changes for a week or two to ensure your water quality is not poor, investigate if there are no causes for the poor water quality ( rotting plants, dead fish/snail) and you will see.
If the fish swimming ok, not twitching and not "staying behind" in the current, it is not old yet and can get better, unless it is some disease we have not yet identified. The round ones actually look a bit fat to me, could be they are full of eggs or overfed, if the female has eggs it can look like it has a bump on the bottom of the belly, that was my experience.
With the light you had, you are missing on their hues. In a cold white light you can see bluish or purple hues in their side. And the amazing red tips of their fins !
Beastije
Fish Addict
Though agreed with the rest of the opinions here, please add some plants to the tank, this is not natural for the fish at all
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