Corydoras acting wild

[Fresh]

I bought one of the value packs from liveaquaria.com and it came with 3 cory's. It's been a short time but they're acting pretty wild by swimming fast up & down on the front glass. All the one's I've seen in the stores just chill out at the bottom. I do feel like the current is too much in my tank as I have a Fluval 306 in a 27g cube tank so I wonder if that's the issue? 

[HH Morant]

My corydoras sometimes dash back and forth on the front glass. I don't think it is an indication of problems. They have done it less and less over time. Maybe they calm down as they settle in.

[lefty o]

a lot of people call that glass surfing. some cory's do it, some dont. generally it is nothing to be concerned about.

[Fresh]

Cool. thanks. Just wasn't sure as this is my first time having them

I am concerned with the current though, not sure if they like it or if they're actually struggling. The filtration turnover rate is 11x 

[HH Morant]

Because they spend so much time on the bottom, corydoras are less affected by current than your other fish. I have angelfish, so I am also conscious of keeping the flow at a level my fish can tolerate. A lot of plants (real or plastic) and structures (wood, rocks, etc.) can help interrupt the flow and create some calmer spaces.

I think high flow rates are overrated. The volume/surface area of your filter media is more important than a high flow rate. If your flow rate is so high that it is bothering your fish, then maybe you should make a change.

[Fresh]

I have a good amount of plants/decor but it doesn't seem like it has an affect on the current imo. I think the issue is the square design so there's no real dead spot. With a rectangle footprint I feel like dead spots are easily attained. The fish don't seem bothered but it does look like they're constantly swimming

[Fresh]

I'm not sure why the image uploads upside down.

[lefty o]

as long as there is somewhere in the tank fish can get out of the current, its not too big of a deal. its nice to turn over the tank. i like a couple times an hour worth of flow, 11x is a bit excessive.  if you can adjust it, i myself would probably throttle it back to about half, and see how things work like that.

[Fresh]

I knew it. Unfortunately there's no adjustment. The filter came with the tank and I believe the previous owner had a saltwater setup which explains the high output. I know piranha's benefit the most with a high output but this is my first community tank so I did suspect 11x was too much from the beginning

I have been thinking about adding a sponge filter to the inlet though. Not sure what I can do with the outlet, maybe add some holes?

Thanks

[Odd Duck]

On 7/1/2021 at 12:01 PM, Fresh said:

I knew it. Unfortunately there's no adjustment. The filter came with the tank and I believe the previous owner had a saltwater setup which explains the high output. I know piranha's benefit the most with a high output but this is my first community tank so I did suspect 11x was too much from the beginning

I have been thinking about adding a sponge filter to the inlet though. Not sure what I can do with the outlet, maybe add some holes?

Thanks

I doubt your flow rate is going to bother cories.  Some seem to really enjoy playing in current.  Don’t worry, the intermittent dashing around is perfectly normal.
 

That being said, adding holes or finding tubing that fits and doing a custom outflow can work.  You can also create a baffle around the outflow to disperse the flow.  They make pre-filter intake covers that should be fairly easily adapted to be a baffle over an outflow.  Some are intended to go over a sponge pre-filter, some are just a wide, screen type pre-filter themselves.  You won’t need the sponge filter itself, just the cover or screen pre-filter.

[Odd Duck]

Here’s one option.  I didn’t search out best price, just a link. 

Edited July 1, 2021 by Odd Duck

[Odd Duck]

Another option.  Found both and others on Amazon.  It won’t let me post an actual link to the Amazon items.

[Fresh]

On 7/1/2021 at 1:43 PM, Odd Duck said:

I doubt your flow rate is going to bother cories.  Some seem to really enjoy playing in current.  Don’t worry, the intermittent dashing around is perfectly normal.
 

That being said, adding holes or finding tubing that fits and doing a custom outflow can work.  You can also create a baffle around the outflow to disperse the flow.  They make pre-filter intake covers that should be fairly easily adapted to be a baffle over an outflow.  Some are intended to go over a sponge pre-filter, some are just a wide, screen type pre-filter themselves.  You won’t need the sponge filter itself, just the cover or screen pre-filter.

I just realized the on/off valve is actually the flow control valve 🙈. I did a search and came across some articles talking about it, I feel like an idiot lol. I will set it halfway when I get home and see how it goes. I might still get the sponge filter though

Thanks!

[Fresh]

On 7/1/2021 at 1:50 PM, Odd Duck said:

Another option.  Found both and others on Amazon.  It won’t let me post an actual link to the Amazon items.

This one's real nice!

[Odd Duck]

I thought this was the better option, too.  Seems like it would disperse flow better.

[Fresh]

Looks a lot more fitting too. Would look great with the rest of the parts

[SarahO]

My cories do that all the time. I once read that they do it when they are happy, but I don’t know if that is true or not. It just seems like the get the zoomies sometimes.

[Phantom240]

If your filter is using a spray bar, point the spray bar backwards toward the glass, and it'll help tame the current. Or you can drill the holes out larger. I drilled mine AND face it toward the glass, and it calms things down a lot. I have a 407 on a 45g bowfront, and my cories aren't ever bothered. Sometimes they'll actually swim up the glass where the current is. 

[Fresh]

Eventually I will be getting a spray bar but I was able to turn down the flow. It's been noticeable so we will see how it goes now

[starsman20]

On 7/1/2021 at 11:18 AM, Fresh said:

I have a good amount of plants/decor but it doesn't seem like it has an affect on the current imo. I think the issue is the square design so there's no real dead spot. With a rectangle footprint I feel like dead spots are easily attained. The fish don't seem bothered but it does look like they're constantly swimming

Wish I could gt my substrate to stick to the top like that.

[starsman20]

On 7/1/2021 at 12:50 PM, Odd Duck said:

Another option.  Found both and others on Amazon.  It won’t let me post an actual link to the Amazon items.

what did you search for?  This looks interesting.

[Odd Duck]

That popped up under “powerhead prefilter”.  The metal one under “prefilter screen”, if I remember right.

[vinny]

I have 6 panda Cory in a 10 gal they do this more when they are young. Idk why it’s just them being silly. No problems to worry about.

[gardenman]

I've always had a suspicion the glass surfing has something to do with migration. Their instincts are saying "head this way," but they keep finding this glass wall blocking them, so they swim and down it trying to find a way past.