I have a 10 gallon tank with 4 platys and 5 mollies. Does this make it overstocked? I am buying a 20 gallon tank soon, but I have to let it cycle.

It depends on how big your Mollies are. If they are less than 2 inches long, no. If greater than 2 inches yes. When you move to your 20G I would get 3 or 4 small Corys for picking up any food that falls to the bottom and a couple of Otos for Algae cleanup.

Only one of my mollies are longer than 2 in, and it's about 2.5 in. Thank you for the advice!

Yes it is overstocked. As you can tell from your other thread you have lost 1 molly already. What kind of water changes do you do? You will need to do plenty till you get the 20 gal and get it cycled. Before you put any small cories or oto's in the new tank make sure it is established good or you will be loosing fish again.

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Even if every one of your Mollies was only 1", you'd be nearly overstocked. If you go by the main rule out there, and it is just barely a guideline and nothing more, it is one inch per gallon. Your tank is a 10g tank, which is measured all the way to the top edge. Since nobody usually runs them that full and you have to take into account the water displaced by gravel and anything else you put in the tank, you probably have about 8 gallons of water. If you went by that rule, just 5 Mollies would have you overstocked (avg adult size approx. 2").

The rule is not perfect and doesn't apply to fish the size of a Molly, really. It also should not be over-ridden by general minimum tank sizes for a given species. For example...min. tank size for an Angel is 20g. Other factors to consider also.

with normal tanks you probably are overstocked.

but it depends on how the tank is setup.

heavily planted tanks can support that bioload.


my .02

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fw leiden since 1979, fo salt since 1979, mixed reef 55g 2002-2009. Strong emphasis on the tank taking care of itself. Balanced with plant life, no water changes, tap water, no filters in FW. Only dosing calcium, alk, mag in marine reef tanks. http://www.aquariumforum.com/f15/my-...ods-26410.html
recent tanks (till 2009) 7 years- 10g FW leiden 7 yrs, 55g mixed reef 7, 2 yrs, 20g FW leiden, 10 g fw leiden , 29g mixed reef, current tank 55g leiden

I dont know if the maths is the same but in the UK we recommend 1cm of fish per 1 litre in the tank.

Also depends how mature the tank is, ive had tanks manage to maintain the bioload of a bit of overstocking during emergencies with no changes to parameters. But i guess that was luck more than anything. But my tank had sufficient planting so i guess that helped things.

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