What happens when...

[StyleUK]

What would happen if a tank was heavily overstocked, i'm not talking about my overstocking, just in general. When I refer to overstocked im thinking about 2/3" of fish per 1" of tank.

What are the effects of this?
How long can the fish last?

 

[QTOFFER]

In an overstocked tank, there is more ammonia-producing bioload than the nitrifying bacterial colony can handle. For most fish under three inches in length, 1 inch per gallon is a useful rule of thumb. However, in the case of some particularly messy fish (large cichlids and goldfish), the 1 inch per gallon rule does not hold true. For instance, two 3 inch goldfish in a 10 gal is way overstocked from a bioload point of view.

Bioload overstocking may result in detectable ammonia and nitrite levels, as well as long term elevated nitrate levels. Ammonia burns gill tissue and nitrite is an asphyxiant - much like carbon monoxide is to people. Fish can adapt to slightly elevated levels of ammonia and nitrite, and to very high levels of nitrate, but over time this will take a toll on the immune system and general health. Eventually, the fish will start dying off from opportunistic infections.

Another form of overstocking that is really not related to bioload can be caused when the fish are simply too crowded. This is a concern with with elongated fish that require large tanks so that they can swim and turn around comfortably. Also, some cichlids (even small ones like shell dwellers and convicts) need more than 1 gallon per inch because of their aggressiveness and relatively large territorial needs. This kind of overstocking leads to fighting, stress, and disease.

 

[redwhiptailplec]

Well it depends on a few things, what size are the fish? You could keep 100 Neons in a well filtered 50 gallon with good filtration and PWC, but keeping 8 13" Oscars which equates to the same number of fish inches would be completely and utterly ridiculous.

We often see over crowding in LFS, with feeder fish, with Oscars certainly they keep dozens of small Oscars in the tank and the water always looks awful, with Neons and Danios etc. Also with aggresive African Ciclids where the overcrowding apparently helps lower incidences of aggression between fish.

Personally I think in the long run you would have a lot more deaths your fish would be much more prone to disease etc. and you would need to do enough PWC for a discus tank in order to keep the water clear let alone clean.

 

[StyleUK]

Thanks for the info.

Just to let you know, my overstocked tank, is clear, non-aggresive, clean, and all the water paramaters are fine! I do a PWC of 30% every 3days, and all the fish are perfect!

 

[Toirtis]

Which do you consider your 'overstocked tank'? And severe overstocking, particularly with Malawi cichlids, often cuases no aggression, as the fish are simply too crowded and stressed to be territorial.

As far as your overstocked tank showing no aggression and having 'perfect' water, it is possible, with overfiltering and frequent water changes....but just because you can do something does not mean that you should.

 

[StyleUK]

My overstocked tank would be my larger one. I know that your not ment to overstock your tank, and it's best to slighty understock your tank, but when I first got the tank I knew nothing, so I went out and braught some fish that I liked, after a while to looking stuff up on the net I found this place, and started to see many stocking questions, I realised my tank was overstocked and could only get worse with the common pleco and the others still growing. I've grown attached to my fish, so I really did'nt want to move any. I know it seems crule to the fish, but as I said they're showing no signs of aggression and look fine. So maybe my tank is just well balenced or i've just been lucky, eaither way i've learnt not to do it agiain.

 

[Toirtis]

I realised my tank was overstocked and could only get worse with the common pleco and the others still growing.

You have that correct...that pleco, under good conditions, with proper food and room, should hit 12" within a year, 16"-18" by 24 months....at which point he will likely be as long as your tank.

I've grown attached to my fish, so I really did'nt want to move any. I know it seems crule to the fish,

And so it is....you should think about what isw best for the fish, not what is best for your personal 'attachments' to the fish.....perhaps you should consider a larger tank...something along the 230L size.

So maybe my tank is just well balenced or i've just been lucky,

I would guess #2, so far...but things are likely to change as the fish grow...then what?

eaither way i've learnt not to do it agiain.

But why do it now, since you possess the knowledge to rectify things?

 

[StyleUK]

Yea, my parents are getting a large tank soon I think 150gallons, maybe more.

I'll definately move or sell my pleco, it's already 8", i'm already saving for a new tank, but money is a big problem in the UK for kids like me, we don't really get paid a lot for jobs etc, and me being only 15, it's quote hard to make enough money to buy a large tank as we're talking about £250 here. I'm not sure why, but large tanks in the UK cost loads, but when I look at US sites they have tanks twice the size for half the price.

So i'm stuck until I get some money.

I'll maybe give the pleco back to the LFS, but, i've asked about giving them my balloon molly fry and apple snail babies, but they've said no, so i'll probably be stuck with him for another few weeks.

Sorry i'm such a bad aquarist.

Thanks for putting up with me.

 

[SteveM]

First, let me say that I agree with everything toirtis has said.

That being the case, I would imagine that if you do find a home for the pleco, the remaining fish will be much better off in your tank than they would be living at the LFS. For that matter, even if they got sold they are likely to fall into worse condidions than you are giving them. An overstocked tank in the hands of someone who knows and cares enough to keep the water params good is better than most tanks I've seen. And this is from the mouth of a devout understocker.

But that pleco really has to go

(edit) Oh, I just looked up the rainbow shark, and he has to go too - you really are/will be badly overstocked. OTOH, as he gets bigger he may clear out the tank for you .