Harlequin rasboras and Pygmy Cory help

I have 9 harlequin rasboras and 9 Pygmy cories in a 20 gallon tank with an aqua clear 50 HOB filter. It’s somewhat planted and should have plenty enough hiding spaces. Water parameters are 0 ammonia and nitrite and 20 nitrates. The ph is around 7.5. I do a 50% water change every week and gravel vac the surface of the sand every time. I feed them every night with the light on and unplug the filter, however they don’t always eat and they won’t eat until the hikari micro pellets start to sink. The harlequin rasboras don’t colour up much at all and tend to sit still, sometimes at the back of the tank and sometimes at the front. Is this just how they are or am I doing something wrong? I am really struggling to figure out why they do this.

 

The light may be too bright for their liking, is a possibility

 

Looks like you have duckweed? They probably didnt see it

 

Looks like you have duckweed? They probably didnt see it

I do but I will lower the light level regardless as the light could still be too bright and I’m at my wits end.

 

They are naturally mid-level feeders, so they won't forage among the duckweed to look for food. Just make a small clearing among the duckweed and drop the food into the water, they will find it eventually.

 

I have 9 harlequin rasboras and 9 Pygmy cories in a 20 gallon tank with an aqua clear 50 HOB filter. It’s somewhat planted and should have plenty enough hiding spaces. Water parameters are 0 ammonia and nitrite and 20 nitrates. The ph is around 7.5. I do a 50% water change every week and gravel vac the surface of the sand every time. I feed them every night with the light on, 30 minutes before lights out. The harlequin rasboras tend to sit still, mostly at the front of the tank if they are not stressed. They tend to school very tightly at all times and only break off the main group in groups of 3 or more. Most schooling fish tend to be more active and not school when stressed. I am really struggling to figure out why they do this, is this just how they are or am I doing something wrong? I dimmed the lights and that helped them get closer to the surface and more out in the open. When the lights are off they seem to be more willing to be out in the open and are braver, pecking the top of the water and splitting up. They still are pretty inactive though, is it just the tank size? I also lowered the filter flow tonight to see if that would help.

Regarding the Pygmy cories, I counted a week ago and saw 8, since then I have seen a max of 7. I feed them four sinking Aqueon shrimp pellets every night and they have only really eaten 1 or 2 each night when they used to eat all 4, and some of them look rather skinny. There are only a few that look thin and the rest look really round. is something wrong with them?

 

The schooling fish that I own rarely schools and normally when they are stressed.

 

I have 9 harlequin rasboras and 9 Pygmy cories in a 20 gallon tank with an aqua clear 50 HOB filter. It’s somewhat planted and should have plenty enough hiding spaces. Water parameters are 0 ammonia and nitrite and 20 nitrates. The ph is around 7.5. I do a 50% water change every week and gravel vac the surface of the sand every time. I feed them every night with the light on, 30 minutes before lights out. The harlequin rasboras tend to sit still, mostly at the front of the tank if they are not stressed. They tend to school very tightly at all times and only break off the main group in groups of 3 or more. Most schooling fish tend to be more active and not school when stressed. I am really struggling to figure out why they do this, is this just how they are or am I doing something wrong? I dimmed the lights and that helped them get closer to the surface and more out in the open. When the lights are off they seem to be more willing to be out in the open and are braver, pecking the top of the water and splitting up. They still are pretty inactive though, is it just the tank size? I also lowered the filter flow tonight to see if that would help.

Regarding the Pygmy cories, I counted a week ago and saw 8, since then I have seen a max of 7. I feed them four sinking Aqueon shrimp pellets every night and they have only really eaten 1 or 2 each night when they used to eat all 4, and some of them look rather skinny. There are only a few that look thin and the rest look really round. is something wrong with them?

the rasboras could be eating the shrimp pellets.

 

I was going to suggest floating plants to cut down the light in the tank, but it looks like you already have some. Was the photo taken after you dimmed the lights? Seems really bright to me, but that may be my preference

It looks like you mostly have low light plants, so dimming the lights might be the answer. Also more plants and hardscaping might help them feel more secure. There would be no harm in dimming the lights way down for a day or two or three to see how they react.

I wonder if adding a background would be helpfull.

 

The schooling is normal for HRs, at least in my experience. Mine school way tighter and more than any Tetra I've kept except Rummy Nose. My Brilliant Rasboras also school that way too.

As for the inactivity, that does seem a bit more strange because HRs in the tanks I have them in are very active. Have you tried giving them flake food? They look like a pack of piranhas when I drop the flakes in.

Perhaps a background could help as suggested.

 

Maybe the Harlequins just found their favourite spot. Mine are in a more open environment without plants just wood and they are active and as likely to be seen spread out as in a tight shoal. Temp is 80F. They are found in the upper half of the tank more often than the lower half. They mainly stay in the open but can retreat to shady areas or behind wood if they wish. I know their colours are more deep and vivid in lower light as I have kept them before but mine don't seem bothered to be in moderate light. The current is moderate like a slow river, turnover is x5. I rate them highly. They are the best shoaling fish I have kept in this tank. I have Cardinals in my planted tank. I like these too and they stay mostly in the bottom half.

 

The schooling is normal for HRs, at least in my experience. Mine school way tighter and more than any Tetra I've kept except Rummy Nose. My Brilliant Rasboras also school that way too.

As for the inactivity, that does seem a bit more strange because HRs in the tanks I have them in are very active. Have you tried giving them flake food? They look like a pack of piranhas when I drop the flakes in.

Perhaps a background could help as suggested.

They go nuts for food but just sit there otherwise

 

Please stop making thread after thread with slightly different titles and problems. Members trying to help go nuts(at least I am). Stick to one or two threads, provide all information and members will react.

 

Please stop making thread after thread with slightly different titles and problems. Members trying to help go nuts(at least I am). Stick to one or two threads, provide all information and members will react.

This is a different tank than the dead corydoras if that is what you are referring to. Would it be preferable to merge those topics into one thread? My apologies, I have a lot of what would probably be small and specific questions. I also sometimes have a post die before I really get an answer on certain things so what can I do when that happens besides repost? Again my apologies, I don't intend to frustrate anyone. especially those kind enough to help me.

 

No apologies needed but please concentrate questions, info and answers in one or two threads.

 

I bought 6 Harlequin rasboras and they are quarantining in a 75 gallon with some lemon tetras, angelfish, corydoras and thicklip gourami. These rasboras are way more brightly coloured then my other harlequin rasboras and are much more active with very little to no glass surfing. I will be adding them to the 20 gallon to see if they stay as active. If they don't stay as active I am thinking it may be the tank size, it could still possibly be other things such as temperature or the tetras being active that spurs them into action. The fish in the 20 gallon have returned to their normal behavior, and actually hang out more dead center in the tank which is completely wide open. The lighting in both the tanks seems to be similar and the amount of cover doesn't seem to be bothering them. I will continue to monitor the situation but those are currently my thoughts, any ideas or suggestions are welcome.