So, I thought I would provide what I've learned in hopes that it helps others.

**Stocking Ratio:**

Of course all of the information out there says minimum of 8 to 12 Exodons, and some provide a minimum aquarium size, but no website would correlate how many Exodons you could have for a specific aquarium size. Of course Exodons are not like your typical fish, and many say they need to be over-stocked (compared to the old 1" of fish per gallon rule) without any guidance. So, I surveyed the internet, including forums and youtube, and anywhere I could find where Exodon owners would list their current stock and their aquarium size and did some bench marking. I took all of this data, calculated the gallon/fish ratio, fit it to a normal distribution, and calculated the standard deviation. Here's what I found:

The average (and therefore most successful) stocking ratio is

**3.00 gallons / Exodon**with a minimum of about 10 Exodons, which means the minimum aquarium size is 30 gallons.

+1 Standard Deviation (Understocked): 7.58 gallon/exodon.

-1 Standard Deviation (Overstocked): 1.87 gallon/exodon

Most extreme cases I found from my survey:

Understocked: 11 Exodons in a 118 gallon tank (10.7 gallon/ exodon)

Overstocked: 90 Exodons in a 90 gallon (1.0 gallon/exodon)

I went through all of this trouble because one day my exodons just stopped eating, and it wasn't until I solved a couple issues that they went back to their normal aggressive selves. Due to the wide range of stocking levels and misleading info I've found online on exodons, I had thought that my tank setup was perfectly fine. After I did this analysis, I realized how overstocked my tank was.

My previous tank setup was a 29 gallon with 17 exodons (1.7 gallon/exodon). I had 20 initially, but aggression and overstocking changed that. Due to my tank being overstocked, my fish stopped eating well, and instead focused their aggression on attacking the smallest fish in the school. Once I found that my tank was nearly 1 standard deviation away from the norm (that's about 68% above average stocking levels for those that don't use standard deviations much) I realized that a change in my stocking levels would probably help. So I upgraded my aquarium to a 55 gallon which put me marginally understocked at 3.2 gallon/exodon. I knew when I went to a larger tank size, I would also need a better filter, which I believe my previous setup didn't have sufficient filtration as well.

Most websites will recommend somewhere between 3x to 10x GPH required (example: a 10 gallon aquarium would need enough filtration to produce 30gph to 100 gph). Again, since the recommendation varied so much, I sought additional information. I focused on recommendations for planted tanks, since my tank is planted, and it seems that the average recommendation for a planted tank is about 5x-6x GPH.

However, I found an extremely useful tool online, that allowed me simulate and try out various filters until I found one that met all of my aquariums filtration needs, for my specific stocking level and aquarium size/shape. I'd suggest you check it out:

http://aqadvisor.com/

I ended up getting an Eheim Classic 2217 (264 GPH) to go with my Eheim Ecco 2232 (127 GPH) for a total of 391 GPH, which on a 55 gallon is about 7x GPH. The water parameters are much better now, and that in combination with the larger aquarium size has caused my exodons to be less stressed. They are now eating very well, and are back to their usual aggressive selves.

Sorry for the long post, but hopefully this info helps other exodon owners out there.

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This post has been edited by **Quad**: 05 September 2014 - 11:12 PM