Foul Tank Smell

[Lola&Spike]

I have a 47 gallon tank with three glofish tetras, a goldfish comet, and then two small bottom feeders that look like plecos but aren't, to which I can't identify what they are. I also have a "Colombian Shark"/"Black Fin Shark".
 
Before I got the two small bottom feeders, and Colombian shark, my tank had been giving off an odor. My mom says it's just fish, and that animals just stink. Which, it could be. I've never had a fish die or get sick, but I have only had it for a year. The fish all seem happy and healthy, they all eat, swim around, but not erratically. 
 
Is there any advice as to how I can eliminate this smell, and what it could be?

 

[Akasha72]

is it just a composty type smell? If so it's perfectly normal and you don't want to try get rid of it. A tank that smells like that is a happy healthy tank

 

[Lola&Spike]

Yeah, a little. Thank you for your help! I always thought it was weird because most sources said the tank should have no smell at all.

 

[fluttermoth]

Much as I hate to disagree with someone's mum, your mum is wrong; animals don't just stink. Of course, most have a certain odour, but it should only be very slight; certainly not unpleasant or overwhelming. If it is, it shows there's something wrong; either your animal is sick, or your husbandry isn't up to scratch.
 
In the case of fish tanks they will, as Akasha rightly says, have a very slight composty or earthy smell; but you should only be able to smell it if you lean right over the tank and sniff.
 
If it's at all unpleasant, or 'fishy', or you can smell it just in the room, something is wrong.
 
I can tell you that your tank is, unfortunately, quite badly stocked. The shark is going to outgrow your tank, and is not compatible with your other fish. Goldfish (unless they're fantail types) should really be in a pond
 
If you post pics of your 'bottom feeders', we can identify them for you. You should always know what fish you have, so you can make sure they get the right care.

 

[Gvilleguy]

The worst smell I ever had come out of a tank I would notice when doing water changes. It turned out to be an artificial ornament (large, fake driftwood) that I had added. I removed the ornament and the tank stopped smelling. Just something to consider.

 

[RobRocksFishTank]

Odors are subjective. One person's slight earthy smell could be another's stench. If the smell is not the "normal" odor that comes from a tank, you need to track down the source. Start with an ammonia test. Also, do some sniffing around to see if the odor is coming from filter media.

 

[ShinySideUp]

"Animals stink"!? Sounds like someone who is not a great fan of animals. I have rabbits, guinea pigs, a dog, pond fish, an aquarium, a wife and my own body -- we all stink in our own way. It's only when the smell is distinctly unpleasant to all that there is a problem.
 
The other day one of my guinea pigs had an odour and it didn't take a vet to tell it was an ear infection -- one side of her head smelt like a guinea pig, the other side smelt like something had died. She is having anibiotics now so should be ok soon.
 
But I digress.
 
The sense of smell in all animals is probably the most important. In humans, just a whiff of a certain scent can bring back a whole raft of memories and emotions. Our sense of smell can save us from bad food, attract us to a mate, tell us if our house is on fire. No one would want to go blind, no one would want to go deaf but in those events one can manage but I think if one lost their sense of smell life just wouldn't have much meaning anymore.
 
** This is only speculation and and a personal opinion, if it is wrong I apologise to anyone who has genuinely lost their ability to smell (and taste).

 

[Tongue_Flicker]

Try using activated carbon with your filtration, do a 25% partial water change and change your feeding routine to a once a day feeding or every other day routine.

Like others also said, animals don't just stink. I keep roaches as feeders and even those don't stink