Loaches Online Forum

I was trying to find this out online last night, but I couldn't find the answer I was looking for.

How many Tetras, (neons, silver tipped, black neons etc) can be put into a 40 gallon breeder tank?? I have 9 at the moment, 3 of each that I named above. I have seen photos/videos of tanks that have what looks like 10-20 tetras in them. But how many is TOO many??

I've heard that they don't produce "As much" waste as other fish. I don't know if this is true. Would it be due to their smaller size??

I would just like to know, to avoid over crowding. Thats the last thing I want to do to my fish. They all seem to be doing very well with each other, space territory wise.

If anyone can give me some insight on this it would be greatly appreciated.

Also I know the 1" per 1 gallon rule.

I have

1 female german blue ram which should reach 3" in maturity
3 neon tetras
3 silver tipped tetras
3 black neon tetras
4 clown loaches
2 yoyo loches

I know that eventually the loaches will need more housing when they grow bigger. That hopefully won't be in the very near future. I wouldn't want to get rid of them due to size, just yet.

Just reading this now- what kind of filter do you have?

There are several aspects to stocking a tank, and knowing when it is overstocked. Here are a few comments, think about them, see how they apply to your tank and your situation.

The 1" per gallon guideline helps for fish up to 2" and only addresses certain needs: Oxygen supply, CO2 removal, Ammonia removal.
With 40" of fish, all up to 2", but not larger, in a 40 gallon tank, then any reasonable filter should keep up enough water movement for exchanging oxygen and carbon dioxide at the surface, and enough locations for nitrifying bacteria to grow on, that remove ammonia. The resulting nitrates should not get higher than 20 ppm between water changes.
Fish that thrive in faster moving water may need a power head or another filter, but that is not covered by the 1" per gallon guide.

Here is some math to make this interesting:
A fish produces waste, and requires oxygen depending on its mass.
When you compare fish by length you need to multiply also width and height.
A fish that is twice as long as another fish is also twice as high and twice as wide. The larger fish produces 2 x 2 x 2 = 8 times as much waste, has 8 times the oxygen need. Still, as long as they are 2" or smaller the 1" per gallon guide is not too far off.

Some other considerations:
Yoyo Loaches ate my Neon Tetras. Yoyos were about 3" long and Neons were about 1"- not quite full grown. I think the Yoyos grew an inch on Neons
Silver Tip Tetras have a bit of a reputation for nipping or pestering the other fish. I did not see that when I kept them, and I did not have very many (just a dozen) but maybe that was enough to keep their pest-like ways to themselves.

Live plants will help with the water conditions in several ways that may allow you to add more fish. Then, taking care of the plants becomes high priority, because they are part of the filter system. I have tried a non-planted tank, and would never go back to that style of aquarium. Instead of adding more fish, you can stretch the time between water changes without the NO3 getting too high when the live plants are removing a lot of the nitrogen.

Schooling fish have some very special behaviors that you will only see when you have lots of one species. A 'Noah's Ark' sort of tank (couple of these, couple of those) is not the best when you are looking at the behavior of a group. Even 3-4 of one species is not enough. I would really suggest that you keep only one school of Tetra, and get a dozen or more of that one species. 2 species in your tank would work, but not any more. Gets too busy with all the different fish, and you cannot keep enough of any one species to really see their special behaviors.

Once the compatibility issue is handled, (remove the larger fish) then look at your water change schedule. If you feel you are already doing too many water changes, and don't have time to keep it up, then the tank is already overcrowded.
If it is really easy to keep the nitrate under 20 ppm, and more water changes (or larger ones) are OK, then it is OK to add more fish.

Ask yourself, "What happens when the power goes out?" Test this, by turning off the filter and anything else that is circulating the water.
The 1" per gallon guide refers to standard shaped tanks, and is fine for long (or breeder) tanks. It suggests that even without the filter, the fish should not be in distress for lack of O2. They may hover a little closer to the top, but they are not gasping and gulping for oxygen up there. If the tank is over stocked the fish will use up the oxygen faster than it is replenished from the air, and they will gasp at the surface. You will be forced to keep the water moving, even if the power goes out. You could get a battery powered air pump to help out. These run all the time, plugged into the wall. When the power goes out the batteries take over and keep the air pump running. This can save the fish in a somewhat overstocked tank.

Think about each of these things, and see which applies best to your tank. Some issues are interconnected, so altering one thing also alters something else.

The way the tank is stocked now will probably be OK until the Loaches grow to about 3". At that point they will need a larger tank, and you can adjust the numbers of the schooling fish.
If any of the Tetras die, then I would restock with the goal of just one species of Tetra.