Overstocking?

[fish_face]

I already have the fish listed below in my tank which is 350 litres/75g (UK)/90g (US) approx.

I would also like to add the following (gradually):

1 more bristlenose or small plec
2 angel fish
2 gold gouramis
1 red-tailed black shark (currently being bullied in a friends tank!)
1 male beta

Would that be overstocking do you think?

 

[sylvia]

2 dwarf gouramis, 3 sword tails, 2 mollies, 10 guppies, 4 clown loach, 1 bristlenose

I wouldn't add the betta cause he would get nipped by the swordtails and mollies and may kill your guppies.
Plecos are territorial and you should only keep one per tank realy... so I'd skip the second pleco.
You could add two gold gouramies but make sure they're not both male... with your dwarf gouramies be careful the new gouramies don't kill them. Try to get two female goldens if you realy want more gouramies or get pearls instead as they are less likely to cause trouble IME.
I wouldn't get the angels. When they are full grown they may eat your smaller guppies and some swordtails will nip their long fins.
You could get the red-tailed black shark but they may harass the guppies and some of your other fish too - it depends on the shark's territoriality and the space it has available to it.
Those clown loaches get very big and you should keep this in mind. When they get larger your tank may be overstocked.

To help your fish get along I would include some caves and things for the pleco and loaches, some large-leaved plants for the shark and some floating plants for the gouramies. Fine-leaved plants would help provide your smaller fish with a retreat if they need to get away from a larger or more aggressive fish. The pleco would also appreciate a bit of driftwood.

If you only added the gouramies and shark you wouldn't be overstocking but be aware of your clown loaches getting considerably bigger.

The only way to be truly certain you are not overstocked is to test your water and make sure your ammonia and nitrites are always at 0 and your nitrates must remain below 40, prefferably below 25, with only one partial water change every week. You can increase the time between water changes with plants which will take up extra nitrates and good filtration and no over-feeding but this is not a replacement for water changes.

I should mention that what I have just written is based purely on my experience and I do know of situations where all the fish you have or want got along together just fine - it's just better to stay on the safe side IMO.

 

[Cheese Specialist]

I personally think it would be fine other than the betta. Bettas should not be ept with anything with long flowing fins. Also, it's often said that different groups of anabatoids (air breathing) should not be kept together.

Plecs are not overly territorial, especially ancistrus, and as long as they are in a big nough tank with enough places to hide that will be fine. Angels also will be ok IMO, they are much less likely to go after any fish if you buy young ones and let them grow with the fish you have.

Your clown loaches will get big 6-8" is normal but they have been known to get as big as 12". However, they grow very slowly after they hit the 4" mark. The only thing that would worry me is that the RTBS might have a go at your clown loaches because of their shape but you could always try. Maybe re-arrange your tank (try to have plenty of wood and caves etc) before you put the RTBS in. They are generally only territorial with other sharks or sometimes shark shaped fish.

Sylvia is right about NitrAtes being an indicator of how fully stocked your tank is but it is not true that your nitrates should be below 40. It's dependent on your tap water for a lot of it, some places in the UK have nitrates of 60 and more and so the level in the tank is not going to fall below that unless it's heavily planted. The best way to check this is to test the nitrates before a waterchange. Record what level they are at. When you come to do your next waterchange test them again and if they are the same or lower than the amount last tested then your waterchanges are covering them (or they are ebing consumed by plants). If they have raised to higher than they were previously (as in were 20 before water change the week before but 30 before this week's change) then you are overstocked, under filtered, over feeding or under maintained.

I would be happy to add the fish (other than the betta and maybe the RTBS) but it's up to you.

HTH