Nano Stocking Question

[threecharacters]

I have a UNS 45S rimless tank. It's only 5 gallons, but it has the footprint of a 10 gallon (45cm x 28cm or 18in x 11in). It's just shallow, only 7 inches deep. Right now, it's an unheated, unfiltered, planted windowsill tank with red cherry shrimp. It's been set up for about 2ish years though I have messed with the planting and stocking some over the years I would say it's well-established.

I would like to get some nano fish for it. I will be adding an established nano HOB filter from a different tank, but it will remain unheated apart from the sunlight it receives. Because this tank has the base dimensions of a 10 gallon I was thinking of stocking it like it was a 10 gallon, but with fewer overall fish because the volume is less. I was thinking of stocking it with just one species of fish. These are some options I was thinking:

• 6ish Boraras sp.
• 6ish Celestichthys sp.
• 6ish Nanostomus marginitus
• 6ish Microdevario sp.
• 2-3ish Dario sp. (stocking depends on if I can get any females or not)
• 6ish Panda Corydoras
• 6ish Dwarf corydoras
• 6ish Ember tetras
• 2-3ish Pygmy sunfish
• 2-3ish Stiphodon gobies (depends on species exactly)
• 2-3ish Sparkling Gourami

I am most partial to the Panda corys, but they also get moderately large. It also depends on what I could get as some of these are kinda rare. I'm also trying to avoid top dwelling fish as the tank is uncovered (nonnegotiable), and I want to avoid any jumpers if I can. This means many betta, killifish, ricefish, rainbowfish/blue-eyes are out of the question. I also don't want to keep anything that will actively prey on the RCS. I think most of these won't be able to take adult RCS and are unlikely to decimate the babies. I haven't gone though to make sure these guys will all be OK in an unheated tank, but I believe many of them will be fine.

What do you think? Are there any fish that absolutely should be removed from this list or any that I should add?

 

[Byron]

The problem issue here is numbers. The shoaling species will be healthier and better off with double most of the numbers, in the 10-12 minimum range. And obviously that is where stocking becomes problematic. Keeping fewer of these species, causing them to be under significant stress, is not something we would advise.

And still on size, the Nannostomus species need more than a 10g. N. marginatus is mentioned, and I kept this fish in a group of 15 in a 29g (30-inch length) and later in a 40g. I would not consider anything smaller for pencilfish.

The smallest tank with fish I have ever kept was a 10g, and in that I had 11 Boraras brigittae and 10 Corydoras pygmaeus. And a couple shrimp that came in the bag with the cories. Well planted, sand substrate, no filter, just a heater. Which brings me to the heater...this depends upon the fish selected, and the room temperature year-round. Some of the listed fish would need no less than the low 70's, and some would need mid-70 to upper 70's.

 

[seangee]

I have a UNS 45S rimless tank. It's only 5 gallons, but it has the footprint of a 10 gallon (45cm x 28cm or 18in x 11in). It's just shallow, only 7 inches deep. Right now, it's an unheated, unfiltered, planted windowsill tank with red cherry shrimp. It's been set up for about 2ish years though I have messed with the planting and stocking some over the years I would say it's well-established.

I would like to get some nano fish for it. I will be adding an established nano HOB filter from a different tank, but it will remain unheated apart from the sunlight it receives. Because this tank has the base dimensions of a 10 gallon I was thinking of stocking it like it was a 10 gallon, but with fewer overall fish because the volume is less. I was thinking of stocking it with just one species of fish. These are some options I was thinking:

• 6ish Boraras sp.
• 6ish Celestichthys sp.
• 6ish Nanostomus marginitus
• 6ish Microdevario sp.
• 2-3ish Dario sp. (stocking depends on if I can get any females or not)
• 6ish Panda Corydoras
• 6ish Dwarf corydoras
• 6ish Ember tetras
• 2-3ish Pygmy sunfish
• 2-3ish Stiphodon gobies (depends on species exactly)
• 2-3ish Sparkling Gourami

I am most partial to the Panda corys, but they also get moderately large. It also depends on what I could get as some of these are kinda rare. I'm also trying to avoid top dwelling fish as the tank is uncovered (nonnegotiable), and I want to avoid any jumpers if I can. This means many betta, killifish, ricefish, rainbowfish/blue-eyes are out of the question. I also don't want to keep anything that will actively prey on the RCS. I think most of these won't be able to take adult RCS and are unlikely to decimate the babies. I haven't gone though to make sure these guys will all be OK in an unheated tank, but I believe many of them will be fine.

What do you think? Are there any fish that absolutely should be removed from this list or any that I should add?

• Boraras sp.
• Celestichthys sp.
• Nanostomus marginitus
• Microdevario sp.
• Ember tetras
• Dwarf corydoras

I happen to keep all of these species and without exception they should all be in bigger groups than 6. My starting point on all of these is minimum 20, but I guess 10 would be OK. Ideal conditions for boraras are too soft and acidic for RCS although the boraras will be ok in slightly harder water (but it still needs to be soft). IMO Celestichthys would be the best bet as they are not too active and ok in a fairly wide range of parameters. They will feed on shrimplets but won't be able to catch most of them. In return the shrimps will feed on CPD eggs and will probably find them all

• Sparkling Gourami

I have these too. They will actively hunt and kill RCS until none remain. They are also quite aggressive (to each other) and need plenty of space to hide from each other. I would get one, a pair may work in such a small space but it may end up with only one survivor. Ruled out anyway because of their feeding preferences.

Can't comment on the rest because I never kept them.

 

[threecharacters]

The problem issue here is numbers. The shoaling species will be healthier and better off with double most of the numbers, in the 10-12 minimum range. And obviously that is where stocking becomes problematic. Keeping fewer of these species, causing them to be under significant stress, is not something we would advise.

And still on size, the Nannostomus species need more than a 10g. N. marginatus is mentioned, and I kept this fish in a group of 15 in a 29g (30-inch length) and later in a 40g. I would not consider anything smaller for pencilfish.

The smallest tank with fish I have ever kept was a 10g, and in that I had 11 Boraras brigittae and 10 Corydoras pygmaeus. And a couple shrimp that came in the bag with the cories. Well planted, sand substrate, no filter, just a heater. Which brings me to the heater...this depends upon the fish selected, and the room temperature year-round. Some of the listed fish would need no less than the low 70's, and some would need mid-70 to upper 70's.

Interesting, I kept Nannostomus marginatus in a 6 gallon many years ago. It was quite an odd tank though, 30in x 6in x 6in, I think. I think I had 8 of them and they seemed to do quite well until I added a bit too much leaf litter causing an ammonia spike and dropsy. They didn't seem space restricted and spent more time hovering than actively swimming, but maybe that's because the tank was too small? I guess the fact that that tank failed was a bad sign. I can strike them from the list for now.

Seriously fish seems to think that most of these fish are OK at 20 C on the low end, but this could just be a generic copy and pasted suggestion. Do you mind sharing which you think need higher temps?

Edit: It looks like the Nannostomus need higher temps which makes sense.

 

[threecharacters]

• Boraras sp.
• Celestichthys sp.
• Nanostomus marginitus
• Microdevario sp.
• Ember tetras
• Dwarf corydoras

I happen to keep all of these species and without exception they should all be in bigger groups than 6. My starting point on all of these is minimum 20, but I guess 10 would be OK. Ideal conditions for boraras are too soft and acidic for RCS although the boraras will be ok in slightly harder water (but it still needs to be soft). IMO Celestichthys would be the best bet as they are not too active and ok in a fairly wide range of parameters. They will feed on shrimplets but won't be able to catch most of them. In return the shrimps will feed on CPD eggs and will probably find them all

• Sparkling Gourami

I have these too. They will actively hunt and kill RCS until none remain. They are also quite aggressive (to each other) and need plenty of space to hide from each other. I would get one, a pair may work in such a small space but it may end up with only one survivor. Ruled out anyway because of their feeding preferences.

Can't comment on the rest because I never kept them.

Good to know. My water is quite soft, but not acidic. GH is about 3 deg, KH about 1 deg, and pH is about 7.5. The RCS have been happy enough in this water.

I'll take off the sparkling gourami.

 

[Byron]

Temperature. Reliable sites like SF give a range for each species. In most cases, the thinking behind this is that the species will probably be at their best mid-range, but they should be able to tolerate the upper and lower extremes temporarily if not permanently. Some species may have more variability, but this is a general idea to keep in mind. As an example, taking a fish like Mikrogeophagus ramirezi that is very demanding when it comes to temperature, the range is 80-86F/27-30C with optimum being in the middle. Not every species is this demanding, true, but the principle behind temp ranges is worth keeping in mind.

Temperature is critical for fish much more than birds and mammals because fish obtain their essential body temperature from the water. Ectotherms, as you probably know. Temperature drives the fish's metabolism and determines how well (or not) the fish's physiology will function. Straying outside the natural range for the species will most often cause stress, leading to other problems, and a shorter lifespan. Along the way none of this is particularly obvious, and many aquarists make the false assumption that because the fish are swimming, eating and even spawning, all is well. A dangerous trap to fall into. The fish can only be considered to be at its best when it has what it requires and expects from its environment.

I have frequently seen aquarists alleging that the temperature in the habitats is variable. This too is largely false. The water temperature diurnally is very often no more than a degree or two, if that. The warmth that accumulates during the day is considerable and affects the night temperature. Significant seasonal variation is also false thinking. Under the equator there is not much variation in temperature--at least, not until we came along destroying the environment and causing climate change.

A quick comment on the pencilfish and tank size. I have kept nine of the species in Nannostomus during the past 30 years. N. eques and N. unifasciatus are the only two that can be kept well in tanks smaller than what the other species need. Even so, a 20g is as small as one should go with these two very inactive species. I've witnessed quite a lot of spawning/play/dominance (whichever) activity within groups of either of these species, and in a 29g 30-inch length tank they were clearly running out of space. I moved them into my 40g and from what I can observe they seemed more content. Males of all these species in Nannostomus are territorial and defensive of their territory to varying degrees. They may not be all that active, but they need sufficient space to "be themselves."