Question about amphipods

[Kraig]

I've had tons of amphipods in my tank since setting it up at the beginning of November. With no fish (or anything else) they were very prominent in the tank. I would see them running around at all times of the day. There were some pretty dang big ones in there too.

Last week I added my first fish, three pajama cardinals. I also added a fire shrimp and cleaner shrimp Monday. I've noticed over the last few days that I no longer see the amphipods. I even turned a flashlight on last night to inspect and didn't see anything.

I tried to read up, but didn't find much useful information. I didn't think pajama cardinals ate amphipods, and even if they did, I don't think there is any possibility of them eating the amount that was in my tank within a week.

I know no one can answer this for sure, but any ideas about what is going on. Are they just hiding more because of the added fish? Do pajama cardinals eat amphipods?

Not something I'm worried about, just curious.

Thanks and have a good day!

 

[vetteguy53081]

I've had tons of amphipods in my tank since setting it up at the beginning of November. With no fish (or anything else) they were very prominent in the tank. I would see them running around at all times of the day. There were some pretty dang big ones in there too.

Last week I added my first fish, three pajama cardinals. I also added a fire shrimp and cleaner shrimp Monday. I've noticed over the last few days that I no longer see the amphipods. I even turned a flashlight on last night to inspect and didn't see anything.

I tried to read up, but didn't find much useful information. I didn't think pajama cardinals ate amphipods, and even if they did, I don't think there is any possibility of them eating the amount that was in my tank within a week.

I know no one can answer this for sure, but any ideas about what is going on. Are they just hiding more because of the added fish? Do pajama cardinals eat amphipods?

Not something I'm worried about, just curious.

Thanks and have a good day!

May have starved
They need phytoplankton as a meal to thrive

 

[SlugSnorter]

I've had tons of amphipods in my tank since setting it up at the beginning of November. With no fish (or anything else) they were very prominent in the tank. I would see them running around at all times of the day. There were some pretty dang big ones in there too.

Last week I added my first fish, three pajama cardinals. I also added a fire shrimp and cleaner shrimp Monday. I've noticed over the last few days that I no longer see the amphipods. I even turned a flashlight on last night to inspect and didn't see anything.

I tried to read up, but didn't find much useful information. I didn't think pajama cardinals ate amphipods, and even if they did, I don't think there is any possibility of them eating the amount that was in my tank within a week.

I know no one can answer this for sure, but any ideas about what is going on. Are they just hiding more because of the added fish? Do pajama cardinals eat amphipods?

Not something I'm worried about, just curious.

Thanks and have a good day!

starved, got eaten, or are hiding. likely starved due to newer tank. They will be back once your tank is more mature, either from you seeding them when the tank has more food, or them hitchhiking on anything

 

[HuduVudu]

I would go with eaten. They are pretty good food source for most fish.

I have had populations go down, but they are always present waiting to come back.

 

[MBruun]

Pajama Cardinals are nocturnal and love to eat amphipods during the night

 

[jfoahs04]

They'll never be as visible in your tank when there's fish in it as they were without fish. The fish will both feed on them and consume some of the same food, both of which will reduce the amphipod population. I would also theorize that existing populations will hide far more with fish in the tank (even at night). Without fish, there are no (or very minimal) predatory threats and the little things don't have much to hide from. So the reason you're seeing fewer now is probably some combination of all of those things.

I almost never saw amphipods in my tank until going fallow. Occasionally, I'd catch one in the light at night or see one stuck in my filter floss/fiber, so I knew they were there, but they weren't out and about. Almost immediately after removing my fish, I saw them everywhere and all over everything at all hours (even broad daylight). There's no competition and no threat. I've been Fallow for almost 2 months now and the population has exploded. As soon as I put my fish back in, I expect to go back to only rarely even seeing evidence that they exist. I'd wager it'll be the same for you.

 

[Duncan62]

They'll never be as visible in your tank when there's fish in it as they were without fish. The fish will both feed on them and consume some of the same food, both of which will reduce the amphipod population. I would also theorize that existing populations will hide far more with fish in the tank (even at night). Without fish, there are no (or very minimal) predatory threats and the little things don't have much to hide from. So the reason you're seeing fewer now is probably some combination of all of those things.

I almost never saw amphipods in my tank until going fallow. Occasionally, I'd catch one in the light at night or see one stuck in my filter floss/fiber, so I knew they were there, but they weren't out and about. Almost immediately after removing my fish, I saw them everywhere and all over everything at all hours (even broad daylight). There's no competition and no threat. I've been Fallow for almost 2 months now and the population has exploded. As soon as I put my fish back in, I expect to go back to only rarely even seeing evidence that they exist. I'd wager it'll be the same for you.

My granddaughter like the pods in my scrubber better than the tank. She'll float a piece of food in the cheato and watch the larger ones eat it up. Lol..

 

[Porpoise Hork]

They'll never be as visible in your tank when there's fish in it as they were without fish. The fish will both feed on them and consume some of the same food, both of which will reduce the amphipod population. I would also theorize that existing populations will hide far more with fish in the tank (even at night). Without fish, there are no (or very minimal) predatory threats and the little things don't have much to hide from. So the reason you're seeing fewer now is probably some combination of all of those things.

I almost never saw amphipods in my tank until going fallow. Occasionally, I'd catch one in the light at night or see one stuck in my filter floss/fiber, so I knew they were there, but they weren't out and about. Almost immediately after removing my fish, I saw them everywhere and all over everything at all hours (even broad daylight). There's no competition and no threat. I've been Fallow for almost 2 months now and the population has exploded. As soon as I put my fish back in, I expect to go back to only rarely even seeing evidence that they exist. I'd wager it'll be the same for you.

Agreed.

I have a ton of them in my tank and never see them with the lights on, but wait 30 minutes after they go out and look with a flashlight and you can see them covering the sand bed and rockwork. If they came out during the day time schedule my wrasses would barely be able to swim they'd be so stuffed...

 

[jfoahs04]

My granddaughter like the pods in my scrubber better than the tank. She'll float a piece of food in the cheato and watch the larger ones eat it up. Lol..

Haha sometimes it's the little things. Who cares about that nice coral colony you've spent years growing out when you can watch some bugs eat food?! They're fun to watch. I've been ghost feeding during my fallow period and I've seen them walk off carrying an entire pellet.

 

[Kraig]

They'll never be as visible in your tank when there's fish in it as they were without fish. The fish will both feed on them and consume some of the same food, both of which will reduce the amphipod population. I would also theorize that existing populations will hide far more with fish in the tank (even at night). Without fish, there are no (or very minimal) predatory threats and the little things don't have much to hide from. So the reason you're seeing fewer now is probably some combination of all of those things.

I almost never saw amphipods in my tank until going fallow. Occasionally, I'd catch one in the light at night or see one stuck in my filter floss/fiber, so I knew they were there, but they weren't out and about. Almost immediately after removing my fish, I saw them everywhere and all over everything at all hours (even broad daylight). There's no competition and no threat. I've been Fallow for almost 2 months now and the population has exploded. As soon as I put my fish back in, I expect to go back to only rarely even seeing evidence that they exist. I'd wager it'll be the same for you.

Very interesting.

 

[Kraig]

Agreed.

I have a ton of them in my tank and never see them with the lights on, but wait 30 minutes after they go out and look with a flashlight and you can see them covering the sand bed and rockwork. If they came out during the day time schedule my wrasses would barely be able to swim they'd be so stuffed...

Ha!

 

[Hairyteeth]

I had a crap ton during fallow, wrasse went in and they disappeared immediately when they knew the hunter had arrived…. Still plenty in there with the red flashlight at night but they don’t run out in the open any more, obviously different behavior now

 

[Kraig]

Even before I added the fish I would throw some sinking pellets in a couple of times a week, mainly for a nassarius snail that would eat them. It was entertaining watching those amphipods come out and fight over those pellets that they could barely move. They would scuttle around as best they could until they finally got a piece back to the rocks and hide. Crazy suckers.

 

[Kraig]

Thanks for the replies! Love the interesting stories.

 

[gavinz]

They'll never be as visible in your tank when there's fish in it as they were without fish. The fish will both feed on them and consume some of the same food, both of which will reduce the amphipod population. I would also theorize that existing populations will hide far more with fish in the tank (even at night). Without fish, there are no (or very minimal) predatory threats and the little things don't have much to hide from. So the reason you're seeing fewer now is probably some combination of all of those things.

I almost never saw amphipods in my tank until going fallow. Occasionally, I'd catch one in the light at night or see one stuck in my filter floss/fiber, so I knew they were there, but they weren't out and about. Almost immediately after removing my fish, I saw them everywhere and all over everything at all hours (even broad daylight). There's no competition and no threat. I've been Fallow for almost 2 months now and the population has exploded. As soon as I put my fish back in, I expect to go back to only rarely even seeing evidence that they exist. I'd wager it'll be the same for you.

Really? I looked last night and saw thousands in my 45 gal. I’ve never seen them before so I had to make a post just to make sure they weren’t anything bad! And I’ve got 7 fish in my tank

 

[jfoahs04]

Really? I looked last night and saw thousands in my 45 gal. I’ve never seen them before so I had to make a post just to make sure they weren’t anything bad! And I’ve got 7 fish in my tank

I mean, I'm not saying you won't see any (or even lots), but in my experience, I've always seen a lot more when the tank is fishless.

 

[gavinz]

I mean, I'm not saying you won't see any (or even lots), but in my experience, I've always seen a lot more when the tank is fishless.

I could only imagine! As I watched my brand new diamond goby, that I got yesterday, sifting sand late into the night just accidentally inhaling them lol