Tanks at LFS

[kevine6678]

I work at a pet shop that sells salt water fish and love actually getting paid to do what I love and that it play with fish tanks. Anyhow, I have a couple questions that I am absolutley puzzled by about some stuff at the store I work at.
1) We always get manderin gobies in. I know that they are only supposed to eat copepods but with every single one that we have ever got in I have had no problem getting them to eat frozen food and/or pellets. Why is this? Can they survive off of these foods?
2) We have a couple 20 gal long tanks with wet/dry filter systems hooked up to them. These tanks are where we keep nothing but hundreds of the hermit crabs and snails that we have. These tanks are always spotless (we never even have to clean them) and all that we feed to them is romain lettice every so often which will be completley devoured withing a couple hours. There are no fish in these tanks. When I test the tanks the nitrate is always very high. Why would this be? I thought that cleaners don't add to the "bio load" but when there's that many does that change things?
Thanks!

 

[ophiura]

I would be surprised if you are saying that every mandarin you get in will eat pellets - maybe frozen more likely. Or maybe there is the appearance they are eating it. Hard to say, but IME they did not readily take to it (I also worked at an LFS).
ALL animals add to the bioload of a tank. It is a myth that a clean up crew is nuetral. They eat waste food, but they produce waste. This is a closed system, the waste doesn't just disappear. Some certainly is converted into animal tissue, but in the end, they still produce waste and this ends up as nitrates. In addition, if like many other LFS, the bioballs may not be properly cleaned along with sponge filters or filter socks. Water changes may not be sufficient. There are a lot of possible factors there.

 

[kevine6678]

Originally Posted by ophiura
http:///forum/post/2595598
I would be surprised if you are saying that every mandarin you get in will eat pellets - maybe frozen more likely. Or maybe there is the appearance they are eating it. Hard to say, but IME they did not readily take to it (I also worked at an LFS).
ALL animals add to the bioload of a tank. It is a myth that a clean up crew is nuetral. They eat waste food, but they produce waste. This is a closed system, the waste doesn't just disappear. Some certainly is converted into animal tissue, but in the end, they still produce waste and this ends up as nitrates. In addition, if like many other LFS, the bioballs may not be properly cleaned along with sponge filters or filter socks. Water changes may not be sufficient. There are a lot of possible factors there.
What you're saying about the crab tanks is all true, makes sense, and is sorta what I figured.
I swear to you though, although more often than not I am using frozen brine, the manderins do eat it. I do also use garlic which could possibly be helping them to eat it. I know they are eating it though. Just today I have watched two manderins in separate tanks eat several shrimp. They will suck one in, chew it up, injest it, and go for another one so they are not spitting it out or anything.

maybe they're evolving

 

[ophiura]

I had in my care a large sweetlips.
Another guy SWORE the thing was eating the prepared foods - adult sweetlips are notorious for failling to thrive in captivity (frankly juvi's too). He was really ticked off when the fish died.
He basically didn't watch long enough, which is critical in "professional" fish husbandry (ie in a public aquarium). The fish WAS eating it. But once you watched for a few minutes you would see it eating it...then spitting a bunch of it out.
So it is hard to know for sure if they are in good shape. Brine will not suffice for a long term diet but it would be a good sign if they ate it. It also could depend on the source of the fish, if you had a supplier that worked on getting them to eat this. But overall I would say it is unusual and not the norm really, IME at least.

 

[kevine6678]

You're probably right. Believe me, I'm not planning on buying one or anything, I just thought that it was interesting. I just thought that I should get more opinions on it before telling any customers that they eat prepared foods.

 

[robdog696]

Almost all mandarins will eat frozen brine. But it will not sustain them indefinitely. I have no idea why. Pellets, however, contain all the nutrients they need. Send me one that is eating pellets! A large one! LOL! And Ophiura is exactly right about the bioload. I run a barebottom tank, as I don't believe in cleanup crews. They remove protein from your tank, but add to the ammonia/nitrates. Plus you probably don't have much liverock in the crab tank. The bacteria that lives on the liverock is actually what feeds on the nitrates.