[LithiumKitten]

Hi TFK I'm new to fishkeeping and this forum was recommended to me.

I have a 75L (20G) tank that was set up with no fish in it for 5 months (short version - I was extremely busy and had no time to do anything with it beyond water changes)

I had an albino cory from my first tank, and two weeks ago I put him in. Last week, he seemed to be doing well, so I bought another albino and two bronze corys for him to school with. The new albino adores him and follows him around when he's not doing his own thing. Both of them are doing completely normal cory things - very active, very happy wandering around. On the other side, the two bronze corys don't look great. One is VERY inactive. He sits still most of the time, and when he does move, it's in short bursts and he looks like he's having trouble doing so.The other one is doing slightly better, but still seems so inactive in comparison to the two albinos.

They do seem to be eating - when I go to check the tank after feeding time all four of them are in the area I drop sinking pellets. I just wanted to find out what was wrong with them and if I could fix it. I did take photos - sorry, they were taken with my phone and are too big to post directly.

This is the one that barely moves

This is both of them. The one that barely moves is towards the front

This is the whole setup
I've posted in another subforum about the state of the plants.

Measurements:

KH - 5
Ammonia - 0.25
I did a water change (1/3) after the measurements so that should be fine.
NO2 - 0
NO3 - 5ppm

Water agitation seems normal - there's no film on the surface. I have recently upgraded my chemical filter and half of the bacterial noodles are now the ones that aren't the plain cylinder (I was told to change those out gradually).

I was planning on eventually adding a school of danios and some dwarf gouramis, but I want to sort this out first. Thank you in advance for any feedback and advice

 

[Agent13]

Well it seems like your tank isnt cycled. You shouldn't be showing any ammonia. Try getting an API freshwater liquid test kit. Results are far more accurate then strip tests.
I'd double check your water and if there is really ammonia that is whats stressing your fish most likely. Also corys are not a fan of gravel. They prefer sand. Ill also add, from your pucture i dont think this setup will work for danios. They need more length to swim. They are very active fast swimming fish. Maybe one DG but certainly not more. They dont tolerate eachother in that kind of space.

 

[jaysee]

Well it seems like your tank isnt cycled. You shouldn't be showing any ammonia. Try getting an API freshwater liquid test kit. Results are far more accurate then strip tests.

I'd double check your water and if there is really ammonia that is whats stressing your fish most likely. Also corys are not a fan of gravel. They prefer sand. Ill also add, from your pucture i dont think this setup will work for danios. They need more length to swim. They are very active fast swimming fish. Maybe one DG but certainly not more. They dont tolerate eachother in that kind of space.

Yyyyyyyyup

 

[LithiumKitten]

Well it seems like your tank isnt cycled. You shouldn't be showing any ammonia. Try getting an API freshwater liquid test kit. Results are far more accurate then strip tests.
I'd double check your water and if there is really ammonia that is whats stressing your fish most likely. Also corys are not a fan of gravel. They prefer sand. Ill also add, from your pucture i dont think this setup will work for danios. They need more length to swim. They are very active fast swimming fish. Maybe one DG but certainly not more. They dont tolerate eachother in that kind of space.

Yeah I've been told to change to sand/a darker, smaller gravel for plant reasons as well, so it looks like I'm going to have to do that. I'll recheck the water now, thanks.

Do you have any recommendations for another schooling fish that is quite hardy?

Edit: Also, when I do get new substrate, what would be the best possible way to change everything out without stressing the fish? Do you have any recommendations for substrate?

 

[Thoth]

One is VERY inactive. He sits still most of the time, and when he does move, it's in short bursts and he looks like he's having trouble doing so.

like above the tank seems to be in week 2 of cycling. You also might want to test the tap water to see if that is where the ammonia is coming from.

I have seen similar symptoms with Cory in a cycled tank. I have had them act like one of their pectoral fins was locked in place only able to move in short bursts. These fish were shipped to me and died off over a period of two weeks. I believe that I tried treating them with a broad spectrum antibiotic with no improvement. It could have been Chilodonella but I am an not sure; I lack experience in diseases.

 

[LithiumKitten]

like above the tank seems to be in week 2 of cycling. You also might want to test the tap water to see if that is where the ammonia is coming from.

I have seen similar symptoms with Cory in a cycled tank. I have had them act like one of their pectoral fins was locked in place only able to move in short bursts. These fish were shipped to me and died off over a period of two weeks. I believe that I tried treating them with a broad spectrum antibiotic with no improvement. It could have been Chilodonella but I am an not sure; I lack experience in diseases.

Alright, I'll check the tap water too.

I don't want to mess around with medications because the other two fish are totally fine. Is there any reason two fish would be okay when the other two aren't? Three of them came from the same place.

 

[brownmane]

It could be that your bronze cories are still a little shy. I have 3 lazer striped cories and 2 c. aneaus. They usually stay under the driftwood that I have in my aquarium. Three of them are almost always out as soon as I feed them. The two others come out to eat a little while later. I don't spend a lot of time in the room where my aquarium is, so me being in there spooks them easily. Even after I've had them several years.

 

[LithiumKitten]

It could be that your bronze cories are still a little shy. I have 3 lazer striped cories and 2 c. aneaus. They usually stay under the driftwood that I have in my aquarium. Three of them are almost always out as soon as I feed them. The two others come out to eat a little while later. I don't spend a lot of time in the room where my aquarium is, so me being in there spooks them easily. Even after I've had them several years.

Well my ammonia is reading as 0 - as I mentioned somewhere above, I did a water change as soon as the test showed 0.25 and I have been feeding them less because I'm fairly certain I was overfeeding.

I'm really hoping that they are just shy - some forums say this is the case, some say it's a huge issues. It would make sense that not all fish will act exactly the same, and I have always noticed that albinos tend to be more outgoing. I will just continue to monitor them and keep an eye on ammonia levels.

What kind of substrate do you use? I'm going to need to swap mine out I believe.

 

[brownmane]

How are your cories doing? After looking at your pics, I was wondering if there is a hiding place for your cories. I can't tell if the shipwreck has an area for them to go into or under. Cories do like to have secluded, covered areas. As I mentioned, mine like to sit under a piece of driftwood that is in the tank. I also have plants that help them to feel secure and not so exposed.

My substrate is small pea gravel. I had tossed the idea around about changing it after reading some of the information on this site, but don't really have experience on how to change substrate in an already set up tank. My cories have been in the tank for 3 or 4 years (I don't remember when I got them) and I'd feel horrible if something happened to them because I messed something up.

They live with 7 lemon tetra, which I've had them for a little longer.

 

[LithiumKitten]

How are your cories doing? After looking at your pics, I was wondering if there is a hiding place for your cories. I can't tell if the shipwreck has an area for them to go into or under. Cories do like to have secluded, covered areas. As I mentioned, mine like to sit under a piece of driftwood that is in the tank. I also have plants that help them to feel secure and not so exposed.

My substrate is small pea gravel. I had tossed the idea around about changing it after reading some of the information on this site, but don't really have experience on how to change substrate in an already set up tank. My cories have been in the tank for 3 or 4 years (I don't remember when I got them) and I'd feel horrible if something happened to them because I messed something up.

They live with 7 lemon tetra, which I've had them for a little longer.

I changed the substrate two days ago to a DIY sand substrate that has peat moss and plant fertiliser underneath. It was quite simple and I was able to put them back on the same day. If yours are fine I see no reason to disturb them though. My substrate was quite large, as you can see in the photos, otherwise I would have left it as well.

The shipwreck pieces are both completely hollow, and you can't see it from the photos but the driftwood pieces sort of interlock and there are some hiding places there as well. All of them enjoy hiding out in the shipwreck, and I can only assume the same for the driftwood because sometimes I can't see one or two.

The bronze cory that wasn't sitting completely still is obviously doing much better - he schools with the other two now and comes out much more often. The other one is still doing poorly, but I do think that it has something to do with his swim bladder, so I don't think there's much I can really do anymore.

 

[brownmane]

Sorry to hear that your one cory isn't doing well. Nice to know that the others are enjoying themselves.