Copepods in my tank?! HOW?

I believe that is what they are... i just did a 75% water change the other day to my 20gallon long tank and i was talking on the phone and saw very little white things on my glass and kinda jumping around like fleas and crawling and such... I tried to look up what it could be and they look like Copepods...

What exactly are they?
Are they okay for axolotls?
How did they get there?
Is it bad to have them in the tank and if so how do I get rid of them?

A few weeks ago I had also started to find small snails in my tank and I was shocked as I have not added any new plants for months! (I have both real and fake plants) but as soon as I started finding them I pulled them out and it had been a week and I had only found one and got rid of him too...



Any ideas? Im baffled

Copepods are harmless to your axolotls and are useful microorganisms to have in an stablished tank.
A 75% water change is way too much. You have basically reseted your tank to a non-cycled state and so you should keep a close eye to avoid nitrogen compound spikes.

Azhael said:

Copepods are harmless to your axolotls and are useful microorganisms to have in an stablished tank.
A 75% water change is way too much. You have basically reseted your tank to a non-cycled state and so you should keep a close eye to avoid nitrogen compound spikes.

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Nitrifying bacteria are primarily in your filter and on your substrate/objects in the tank. They are in negligible amounts in the water. I've done near 100% water changes before with zero issues in my fish/amphibian tanks.

I agree though that if they are copepods they should be harmless. The picture isn't loading for me at the moment.

Yes, but a large water change usually means a significant change in water composition which can kill off the biofilm. Particularly so if the water used for the change is untreated.
If you have done such large water changes and have meassured no change in water chemistry afterwards the only explanation is that the water you used for the change was basically identical to the one you took out. Otherwise it would have had an effect on the bacteria since at the very least they would have had to adapt to the new conditions, provided that they could.

DSCF4233.jpg Photo by Tizzo | Photobucket

here is the link this is what they look like


thank you for helping.

AshSeek said:

DSCF4233.jpg Photo by Tizzo | Photobucket

here is the link this is what they look like


thank you for helping.

Click to expand...

I think copepod, but I haven't encountered them often in my freshwater tanks.

Azhael said:

Yes, but a large water change usually means a significant change in water composition which can kill off the biofilm. Particularly so if the water used for the change is untreated.
If you have done such large water changes and have meassured no change in water chemistry afterwards the only explanation is that the water you used for the change was basically identical to the one you took out. Otherwise it would have had an effect on the bacteria since at the very least they would have had to adapt to the new conditions, provided that they could.

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I would think this has a lot to do with water change frequency. If you always change 75%, and you do so at a consistent/frequent schedule (like weekly), the water composition (assuming straight from the tap, hopefully dechlorinated) will be pretty similar.

Even when water conditions are not similar, e.g. when I've adjusted water change frequency or volume, I've not had issues. I've prioritized clean water over matching water conditions exactly between tank and source. My experience may not be true for everyone, but I have done this for a few years on up to about 500 gallons of tanks running at any one time. I'd be interested to know if this is more stressful for axolotls vs. some of the fish I've kept to date.

My main point was merely that I don't think changing more than 50% or whatever amount is automatically bad, but it's probably unnecessary. And it's important to dechlorinate/age/treat the water appropriately depending on conditions.

Have you made any meassurements of water parametres? Because otherwise the absence of issues, which of course is totally plausible, is not necessarily an indicator of bacterial population. In other words you can have a totally uncycled tank and have no issues, that´s entirely possible. However, it is a vulnerable situation and a beginner, in particular, may have problems, which can even potentially be lethal. That´s why i recommended that monitorization of water parametres is ideal, to avoid spikes.

Usually, for stablished tanks the recommended fraction is about 10-20% of the volume, daily, weekly or otherwise depending on volume and number of inhabitants, etc. This allows for stability which permits bacterial activity while at the same time being typically sufficient to avoid the build up of nitrates. Larger water changes are usually unnecessary and counterproductive.

Back to the original question, that is indeed a copepod, possibly Cyclops sp. Totally harmless and benefitial so no need to panic and dismantle the tank to get rid of them, they are useful little things.

Azhael said:

Have you made any meassurements of water parametres? Because otherwise the absence of issues, which of course is totally plausible, is not necessarily an indicator of bacterial population. In other words you can have a totally uncycled tank and have no issues, that´s entirely possible. However, it is a vulnerable situation and a beginner, in particular, may have problems, which can even potentially be lethal. That´s why i recommended that monitorization of water parametres is ideal, to avoid spikes.

Usually, for stablished tanks the recommended fraction is about 10-20% of the volume, daily, weekly or otherwise depending on volume and number of inhabitants, etc. This allows for stability which permits bacterial activity while at the same time being typically sufficient to avoid the build up of nitrates. Larger water changes are usually unnecessary and counterproductive.

Back to the original question, that is indeed a copepod, possibly Cyclops sp. Totally harmless and benefitial so no need to panic and dismantle the tank to get rid of them, they are useful little things.

Click to expand...

I have done measurements but not systematically, at least recently. So it's more than just 'nothing is dead' that I'm basing my comments on.

I'll do some more reading in the other threads or start a new one as to water change volume/frequency re: axolotls. I don't want to de-rail this one any further. Thanks.

Glad to hear these copepods are nothing bad to have in case others encounter them. Would baby axolotls potentially use them as a food source?

I have a hard time understanding tank cycling and things of that nature. I do have a testing kit and have used it once, I always use water conditioner when I change the water.. My main reason for changing it (which I try to about once a month do a bigger water change) is to clean it up and get the poo that I don't catch with my turkey baster... It gets dirty and sometimes orange/brown algae/moss stuff grows on their cave and fake and live plants (which I read wasn't harmful) but it makes it look dirty. I sometimes take out a couple of gallons a week or every other week but not consistently.
But going back to my tank cycling, I've never really done it properly, my axololts seemed to never had a problem with it as far as disease or stress or sickness.
(tho my pink one has started eating my green ones gills just two weeks ago, one per week) I think they just try to both get in the hideaway (they can both fit) but my pink is more dominant and a picky eater. I often see them try to go for the other's worm when I feed them so i think its accidental, her thinking the fluffy gill is a worm. Tho someone said they wondered if my water could have anything to do with it.