Half my fish stopped eating flakes?

lojack

I’ve been feeding omega one flakes (along with other foods) to my fish for a decade. This past 10 days or so the harlequin Rasboras in my display tank decided they don’t like them anymore almost overnight. Is this something that happens? I’ve been keeping fish for over 25 years and it’s a first for me. But I do have some ideas on what’s going on and I’m looking for input and opinions!

1. 10 days ago I moved everything from my 50 gallon planted (10 years old) into a new 125 gallon. Is it possible they’re stressed from the move still?
2. For the first 6 days or so the Rasboras huddled around my large Anubias and just the last couple of days started swimming the full length of the tank. I assume they were uneasy with all of the wide open space.
3. The can of food is near empty and been open way longer than it should. Maybe they decided it was stale?
4. With #3 in mind, the rest of the corydoras and shrimp have no problem eating the flakes. I also have 10 new juvenile harlequins in quarantine that eat it like it’s crack (do you eat crack?).
5. I tried to tempt them with frozen bloodworms tonight. Half the Rasboras attacked the worms and devoured like normal. The other half attacked but acted picky, choosing ones they wanted to actually eat. Again, shrimp and corydoras ate like normal.
6. I don’t feel like it’s parasites, no new inhabitants for over a year (the Rasboras were the newest additions).
7. No signs of illness or disease, no clamped fins or flashing.

I’m open to suggestions. I’m hoping it’s as simple as they’re just still getting used to the new tank layout.

Other obligatory info:
0 ammonia
0 nitrites
10 nitrates
8.2 ph (stable)
Room temp 75-78 F
Inhabitants range 1-9 years old
 

Presidenchill

how did you move them to the new tank. What was your method exactly. And how did you acclimate them and did you use any stress reliever and keep the lights off for a while?
 
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lojack

how did you move them to the new tank. What was your method exactly. And how did you acclimate them and did you use any stress reliever and keep the lights off for a while?
Net straight into the new tank. Same parameters, temp, etc. I did a bunch of water changes leading up to the move to get nitrates as close to 0 as possible to try and get them used to pristine water. No acclimation. Yes lights off, moved in the morning, lights come on in the evening on a timer.

One thing I forgot to add was I reused a lot of old substrate. Even though I rinsed the heck out of it I assume there was a lot of detritus that made it into the new tank. Been doing the paper towel method daily to remove protein film (I think I’m finally getting on top of it, I’ll find out in the morning lol).

The first few days the Rasboras were going after every little floater that would go to the surface. When they realized it wasn’t food they’d spit it out. Is it possible they think all the flakes are detritus now?
 
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Presidenchill

I wonder if eventually survival instincts will kick in and they will instinctively eat. Not sure if you should wait it out or try another method or different food. Do they seem completely uninterested in any introduction of food in the tank? They should be able to "smell" the difference at some point I would imagine.
 
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lojack

I wonder if eventually survival instincts will kick in and they will instinctively eat. Not sure if you should wait it out or try another method or different food. Do they seem completely uninterested in any introduction of food in the tank? They should be able to "smell" the difference at some point I would imagine.
That what I assumed after 10 days that they would be hungry enough to finally eat something. I guess technically they did eat bloodworms, some Rasboras more than others.

A few of them will grab a flake here or there. But the school will swim right through some flakes in the water column and mostly ignore it. However last night I watched for about 15 mins as flakes sat on the surface circling around until I walked away. Came back 10 mins later and they were all gone. I don’t think they all sank and got eaten by the corydoras and shrimp or sucked in the filter that fast (prior nights I’ve watched flakes sit there on the surface for like an hour).

Early on I considered maybe they weren’t used to the new light intensity. I went from a T5HO fixture with super old bulbs to a Finnex stingray 2. But that theory kind of went out with them not eating flakes in the water column.
 
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Presidenchill

I assume you rinsed the substrate in old tank water. And then also looking at #3, have you tried a new can of the same food or switched flakes. It does sound like they just aren't used to the new tank yet. In schooling behavior I assume cliques form and behavior is mimicked so some may not care and follow suit of the more stable group while the others that are sketchy are just grouping instinctively. I'd feel a little safe knowing they ate something rather than nothing at all. Fish can go longer than we think without eating but I'm not familiar with the fish you have either so don't quote me on anything.
 
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lojack

I assume you rinsed the substrate in old tank water. And then also looking at #3, have you tried a new can of the same food or switched flakes. It does sound like they just aren't used to the new tank yet. In schooling behavior I assume cliques form and behavior is mimicked so some may not care and follow suit of the more stable group while the others that are sketchy are just grouping instinctively. I'd feel a little safe knowing they ate something rather than nothing at all. Fish can go longer than we think without eating but I'm not familiar with the fish you have either so don't quote me on anything.
Yeah rinsed in old water to get all the chunky bits out (there sure is a ton of detritus that builds up after a decade even with weekly vacs!).

New flakes was going to be my next step. Figured I’d try the blood worms in the meantime since I already had them for weekly treats (first time since the move).

I did notice that behavior in my quarantine tank. Sometimes I sneak a feed in there without the fish noticing (seems impossible given it’s only a 10g). When one noticed and starts eating the rest follow suit.

I agree on the eating. These guys are well fed and could go a long while without food. Back when we could travel, if we were gone less than 10 days I didn’t bother having anyone feed the tank.

I appreciate all the comments.
 
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FishGirl38

Are you varying their diet regularly? you mentioned you gave them bloodworms, do you mix up their flake on occasion? or do you feed the same brand, same kind, every time?

It barely makes sense with the inhabitants being so mature (I would think this would've occurred awhile ago), but if you feed the same flake all the time, the fish could be lacking in nutrition? I'm partial to omega myself, Fluval is my second go to. I have rainbows and severum in my main community tank (my one severum is picky, and will only eat hikari carnivore pellets...) but for the rest, I switch between the cichlid flake, marine flake, and the 'first' flakes. I switch between the cichlid and first flake as their main go to, and marine for when I want to treat them (the garlic [included in marine flake] is an appetite enhancer for fish).

I also give mine a sinking pellet, for texture variety, as I've got a fair amount of bottom feeders too, I feed fluval cichlid granuls, and fluval bug bites for those guys.

I would think the likelihood that this is the cause is slim, but it might not hurt to feed a few different types of food regularly, if you're not already.

Ultimately, the fish will eat once they're hungry enough. Fish can go for quite a long time (about 2 weeks) without any food as well.
 
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Presidenchill

Yeah rinsed in old water to get all the chunky bits out (there sure is a ton of detritus that builds up after a decade even with weekly vacs!).

New flakes was going to be my next step. Figured I’d try the blood worms in the meantime since I already had them for weekly treats (first time since the move).

I did notice that behavior in my quarantine tank. Sometimes I sneak a feed in there without the fish noticing (seems impossible given it’s only a 10g). When one noticed and starts eating the rest follow suit.

I agree on the eating. These guys are well fed and could go a long while without food. Back when we could travel, if we were gone less than 10 days I didn’t bother having anyone feed the tank.

I appreciate all the comments.

Yea it could be a combination of anything really I tend to have 5-6 different food I alternate with when I feel like maybe they are too full or can use more green or treats or whatever but I know that my previous fish got tired of flakes extremely fast and the pellets are just all around better for their digestive tract. Like you said they picked at the blood worms which is something but I can understand how a week and a half is a long time for them to seem not to be going back to normal. The movement from a 50 to a 125 also means different concentrations of chemicals that we don't test for in the water. There are also, as i believed was just mentioned, certain foods that stimulate "hunger" which are good every once in a while anyway. Also, and this is just a thought, we can eyeball approximately how much a fish has ate but the speed at which they get rid of waste and how much they eat at one time can vary slightly. Maybe some fish are just hungrier than others. I think it's a good sign that when you put food in it was gone when you came back with no sign of it in the substrate or the filter. Seems like a waiting game. I wonder how they'll react once the new fish (more competition) is in the tank haha.
 
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lojack

Are you varying their diet regularly? you mentioned you gave them bloodworms, do you mix up their flake on occasion? or do you feed the same brand, same kind, every time?

It barely makes sense with the inhabitants being so mature (I would think this would've occurred awhile ago), but if you feed the same flake all the time, the fish could be lacking in nutrition? I'm partial to omega myself, Fluval is my second go to. I have rainbows and severum in my main community tank (my one severum is picky, and will only eat hikari carnivore pellets...) but for the rest, I switch between the cichlid flake, marine flake, and the 'first' flakes. I switch between the cichlid and first flake as their main go to, and marine for when I want to treat them (the garlic [included in marine flake] is an appetite enhancer for fish).

I also give mine a sinking pellet, for texture variety, as I've got a fair amount of bottom feeders too, I feed fluval cichlid granuls, and fluval bug bites for those guys.

I would think the likelihood that this is the cause is slim, but it might not hurt to feed a few different types of food regularly, if you're not already.

Ultimately, the fish will eat once they're hungry enough. Fish can go for quite a long time (about 2 weeks) without any food as well.
I’m all in on Omega One lol. Not really a fanboy but it’s what I’ve been using and it’s worked (so far). The Rasboras get flakes 5x a week and bloodworms 1x. The corydoras get omega one shrimp pellets 4x, their brand “algae” wafers x1 (which actually have more protein than anything lol) and bloodworms x1. The whole tank gets one fasting day. The Rasboras typically eat their flakes then hover around the corydoras and pick at the particles that float away so they get a little of everything.
 
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lojack

Yea it could be a combination of anything really I tend to have 5-6 different food I alternate with when I feel like maybe they are too full or can use more green or treats or whatever but I know that my previous fish got tired of flakes extremely fast and the pellets are just all around better for their digestive tract. Like you said they picked at the blood worms which is something but I can understand how a week and a half is a long time for them to seem not to be going back to normal. The movement from a 50 to a 125 also means different concentrations of chemicals that we don't test for in the water. There are also, as i believed was just mentioned, certain foods that stimulate "hunger" which are good every once in a while anyway. Also, and this is just a thought, we can eyeball approximately how much a fish has ate but the speed at which they get rid of waste and how much they eat at one time can vary slightly. Maybe some fish are just hungrier than others. I think it's a good sign that when you put food in it was gone when you came back with no sign of it in the substrate or the filter. Seems like a waiting game. I wonder how they'll react once the new fish (more competition) is in the tank haha.
Yeah it was just kind of an unexpected shock that they stopped eating considering they’re typically voracious eaters.

Haha I don’t know how much competition the newbies will be, they’re pretty young juveniles about 1/3 their size. Been trying to put some size on them before tossing them in.
 
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Presidenchill

Yeah it was just kind of an unexpected shock that they stopped eating considering they’re typically voracious eaters.

Haha I don’t know how much competition the newbies will be, they’re pretty young juveniles about 1/3 their size. Been trying to put some size on them before tossing them in.

Oh ok didn't know they were juvies. Well hopefully you've found some comfort but I definitely wouldn't stop gathering information on those fish specifically and their respective traits. I hope they get back to a regular behavior. My raphael catfish gets into these slumps and wont eat or come out regardless to what I do, then I catch it out of nowhere swimming freely and trying to catch food wherever the others are feeding. Then when it notices I'm looking all my catfish just stare at me and come up to the glass or run around like I'm the devil lol.
 
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lojack

Oh ok didn't know they were juvies. Well hopefully you've found some comfort but I definitely wouldn't stop gathering information on those fish specifically and their respective traits. I hope they get back to a regular behavior. My raphael catfish gets into these slumps and wont eat or come out regardless to what I do, then I catch it out of nowhere swimmingly freely and trying to catch food wherever the others are feeding. Then when it notices I'm looking all my catfish just stare at me and come up to the glass or run around like I'm the devil lol.
I’ve had harlequin Rasboras on and off for the last 10 years and they’re probably the easiest and hardiest fish I’ve ever had. I did consider using the 125g for some bigger boys but I really like large schools of smaller fish. But then I saw some of your fish and now I’m a tiny bit jelly, haha.

That’s funny about the catfish. It actually reminded me that the Rasboras are shying away from me now when I approach the tank. They used to come up like hungry dogs, especially around feeding time. I guess it’s another sign they’re just uneasy in the new tank.
 
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Presidenchill

I’ve had harlequin Rasboras on and off for the last 10 years and they’re probably the easiest and hardiest fish I’ve ever had. I did consider using the 125g for some bigger boys but I really like large schools of smaller fish. But then I saw some of your fish and now I’m a tiny bit jelly, haha.

That’s funny about the catfish. It actually reminded me that the Rasboras are shying away from me now when I approach the tank. They used to come up like hungry dogs, especially around feeding time. I guess it’s another sign they’re just uneasy in the new tank.

Thats a funny phenomenon. I have fish that will end up being really big but I've always been fascinated by the big schools of fish and their behavior. Part of it i think is that when you end up owning big fish your brain sees smaller fish as food for the bigger fish lol. I dont feed my current tank live fish though. I stopped that with my first tank years ago with the advancement of fish food.
 
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lojack

Thats a funny phenomenon. I have fish that will end up being really big but I've always been fascinated by the big schools of fish and their behavior. Part of it i think is that when you end up owning big fish your brain sees smaller fish as food for the bigger fish lol. I dont feed my current tank live fish though. I stopped that with my first tank years ago with the advancement of fish food.
Getting enough smaller fish to make a large school is pretty mesmerizing to watch.

I think that’s the same thought process on both sides... owning a bunch of smaller fish limits my options for a centerpiece fish based on mouth size, haha.

I’ve always been sketched out by feeding live fish. Mainly because of the quality and the possibility of parasites, etc. But then again I’m the same guy that used to feed random flying bugs to my fish when I was younger, haha.
 
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lojack

My juveniles went into the main tank today. I started laughing when the adults joined them and followed their lead around the tank.

Tonight I fed them the flakes. As soon as the juveniles noticed the food then started going at it. It got a few of the adults going too. Most still grabbed some and spit it out. This weekend I’ll pick up some new flakes.

Aside from omega one, anyone have any favorite flakes? Would prefer something economical and not wallet emptying.
 
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Presidenchill

Getting enough smaller fish to make a large school is pretty mesmerizing to watch.

I think that’s the same thought process on both sides... owning a bunch of smaller fish limits my options for a centerpiece fish based on mouth size, haha.

I’ve always been sketched out by feeding live fish. Mainly because of the quality and the possibility of parasites, etc. But then again I’m the same guy that used to feed random flying bugs to my fish when I was younger, haha.

I fed my oscars house spiders the other day and I'm like... I have no idea what could possibly be in that spider
 
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Presidenchill

My juveniles went into the main tank today. I started laughing when the adults joined them and followed their lead around the tank.

Tonight I fed them the flakes. As soon as the juveniles noticed the food then started going at it. It got a few of the adults going too. Most still grabbed some and spit it out. This weekend I’ll pick up some new flakes.

Aside from omega one, anyone have any favorite flakes? Would prefer something economical and not wallet emptying.

That's good they are getting along so far, an unpredictable move like more of the same fish might distract them enough into positive behavior like eating lol nobody wants to be left out of that equation.

That's the only thing I'm not familiar with as I'm a pellet person through and through because of the diet of my fish. I have cichlid flakes but mine mostly spit it out because they know the other food I have. I've always wanted to get into the knowledge of quality flakes but I have no functional use. I know others here will have more experience.
 
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lojack

That's good they are getting along so far, an unpredictable move like more of the same fish might distract them enough into positive behavior like eating lol nobody wants to be left out of that equation.

That's the only thing I'm not familiar with as I'm a pellet person through and through because of the diet of my fish. I have cichlid flakes but mine mostly spit it out because they know the other food I have. I've always wanted to get into the knowledge of quality flakes but I have no functional use. I know others here will have more experience.
The last time I bought pellets was for my gold fish about 15 years ago. I used to pre soak them. Is presoaking still recommended for all pellets?
 
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Presidenchill

The last time I bought pellets was for my gold fish about 15 years ago. I used to pre soak them. Is presoaking still recommended for all pellets?
I've heard of it but I end up just putting mine in straight but then again my oscars have "teeth" in their gills or something like that. I've thought about making a mix tho of different foods once one of my bottles get low.
 
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lojack

Well safe to say the Rasboras seem fine. I got some Hikari micro pellets and threw them in. Turned all the lazy adults into piranhas. Haven’t seen them eat that fast since they were juveniles lol.
 
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Presidenchill

Well safe to say the Rasboras seem fine. I got some Hikari micro pellets and threw them in. Turned all the lazy adults into piranhas. Haven’t seen them eat that fast since they were juveniles lol.
That's great. A variety or change in food will sometimes get them. They probably could see and smell that it was different food. It'll be interesting to see if any traits or behaviors shift with the food also.
 
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flyinGourami

Whenever its feeding time with the hikari micropellets, I swear its like my neons are really just zebra danios in disguise lol.
 
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lojack

Whenever its feeding time with the hikari micropellets, I swear its like my neons are really just zebra danios in disguise lol.
Haha, I thought the same. I used to have zebra danios, too. Wasn’t a fan of their crazy energy lol.

That's great. A variety or change in food will sometimes get them. They probably could see and smell that it was different food. It'll be interesting to see if any traits or behaviors shift with the food also.
For the most part the adults didn’t give a second thought to a bunch of juveniles joining their school. Tonight they were chasing the juveniles away from the micro pellets. I’m interested to see how much I disappoint them tomorrow when I try flakes again, haha.
 
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Presidenchill

I just stocked up on some New life spectrum Thera-A pellets for my oscars. They've grown a little since I got them and their appetite deserves less of a bigger pellet versus more smaller pellets plus new life spectrum in my opinion is just a little step above omega one which is kind of tied with Hikari even tho they've changed some of their recipes and added more corn. I don't know how I feel about my fish and corn. I don't even eat corn lol
 
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lojack

1.5ish week update. All the adult Rasboras are back to eating flakes. Those juveniles tricked them good lol.

Realistically the adults are probably eating normally again because they seem more comfortable now. I’m surprised how long it took them to take to the new tank. Then again it’s in a different part of the room with different lighting and shadows so can’t blame them.

The juveniles on the other hand they’re way too trusting. I can literally grab them with my hands when I’m cleaning the tank and they don’t even flinch. One of the little idiots rode my sponge up to the rim while I was scrubbing and I almost smashed it haha. Thanks all for the replies.
 
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Presidenchill

I figured the stimuli of the Young would trigger them enough. And yeah juveniles are fearless
 
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