Advice on Tank Capacity - How many more Dwarf Loaches

[Soujirou]

Hello, I was wondering if someone could give me advice on whether or not I can add more dwarf loaches to my 30 gallon planted tank. Currently I have:

1 pearl gourami - 4 in (10 cm)
6 harlequin rasbora - 2 in (5 cm)
5 dwarf loaches - 2.5 in (6 cm)

So going by inches of fish per gallon, I am near capacity at 28.5 in of fish. 4 of my loaches school frequently, but there is one that is healthy, but still hangs out by itself unless it's feeding time. I would like to add more to make hopefully make the other more comfortable to school.

A week ago my tank looked like this:



I am always looking to jam more plants in there. It is filtered by an Eheim 2215, but even with it off, the plants prevent any bacteria blooms. Algae growth is pretty low and I never get green water. I was hoping with a planted tank that I could increase my fish capacity. Does anyone believe I can get more dwarf loaches without putting the whole community in danger? If there is any more info you need please let me know.

[Mad Duff]

If I am right your Eheim 2215 is rated at around 92 gallon so the tank is well over filtered so personally I would say you could comfortably make your shoal upto 10 or 12

[Diana]

The inches per gallon guideline is really only appropriate for fish under about 2". It is strictly a guide to how much water is needed to properly dilute the waste between water changes.

When you are considering whether a tank is overstocked look into these issues:

1) Waste management. In an unplanted tank you are the only way the tank is getting rid of nitrates and many other things that accumulate. You use nitrate levels as your guide, and do enough water changes (volume and frequency) to keep the nitrates under 20 ppm. This is also removing fish hormones, and lots of other stuff that we do not measure.

With a well planted tank I would think you would have to add nitrate, so measuring nitrate is not the easy way out. I know my tanks still benefit from water changes, the fish are much happier when there is fresh water in the tank. I do not know if there is something I am removing, or something that I add (from the tap water) that makes the fish so happy, but they sure do swim around like crazy, darting in and out of the incoming water.

2) Oxygen levels. Under normal circumstances your tank will have plenty of oxygen for more fish. The plants are supplying it as long as the tank is lit. Are you adding CO2? Do the fish ever hang at the surface in the morning? (Too much CO2/not enough O2 overnight)
What happens when there is a power outage? With significantly less light the plants cannot make the O2 the fish need. More fish = more of a problem.

3) Fighting, other social issues. I do not see a problem with adding more Loaches. These guys are generally very social and happy to have more friends. As for the one that does not school with the crowd, well, there is one in every crowd. (I have one Clown Loach that is more often by himself, too)

4) Space/territory/caves... if there are enough for all and a couple extra this is good.

[Eyrie]

The "inch per gallon" rule really needs to be viewed as "cubic inch per gallon". On that basis I'd be comfortable doubling the size of both your sid and harlequin shoals, especialy given your filtration.

[Mike Ophir]

I agree, you should be able to house 10-12 quite successfully.

Mike

[Soujirou]

Thank you for your advice. I guess I will buy another batch of six in the future and monitor how well they do.

For nitrates, the only nutrients I add are root tabs because I am trying to keep as little nutrients in the water as possible. They stay around 5 ppm. I change 5 gallons out twice a week.

I am adding DIY CO2 to the tank but the fish never appear distressed. The lights are on for 10 hours (might try 12) so I believe there is enough O2 for them. I can always change the light period or yeast recipe if needed.

I have not noticed any in-fighting. The sids do chase the rasboras a little bit, but the rasboras choose to swim at the bottom of the tank with them. Before I got the sids, they swam in the middle so they must like the sids. The loaches can hide under both logs and I also see them under plant cover behind the large driftwood as well.

[Diana]

Sounds like a nice set up!

I like the idea of a "cubic inch per gallon" guideline. Is it really a cubic inch, though? Most fish are not spherical nor a cube; a fish an inch long is more likely to be perhaps 1/4" to 1/2" high and wide. At this rate a 1" long fish has a volume of closer to .125 cubic inches. A 2" long fish with the same proportions would be 2" x 1/2" x 1" = 1 cubic inch.
Could you keep say... 8 Ember Tetras in a tank, or trade them out on one female Platy?

A 3" long fish would be 3" x 1-1/2" x 3/4" = 3.375 cu in.
Certainly makes the point about the guideline as it is currently stated is quite limited.

[Eyrie]

Interesting you should mention ember tetras.

I have ten, together with eleven Paracheirodon simulans and eight Corydoras hastatus in my 54L/12G tank and don't have any problem with the water quality. Just a standard internal filter, but I do change 30% weekly.

And no, I wouldn't trade any of them for a platy!