Sick Lambchop Raspbora - Any Advice?

[FreshWater1]

Currently one of my seven lambchop's have gone pale and doesn't look too well. They are still sticking with the school and eating but I had this happen about a year ago and the guy just never gained his color back until eventually dying after a week or two. I've attached pics of the fish the camera doesn't really do justice for how much paler this dude is compared to his buddies... Any advice beyond a water change? I really would rather not dump some medication into my community tank for one lambchop... I knew they don't live as long as a lot of fish but he seems too young.

1~What type of fish is afflicted? In addition, please describe what is wrong with the fish to the best of your ability (i.e. cotton like growth, bloated, etc.).
Lambchop Rasbora - losing color / gone pale

2~What are your tank parameters (ammonia, nitrites, nitrates, temp, pH)? Please give exact values.
Steady - planted and water changes infrequent due to steady readings - no ammonia/nitrates/nitrites buildup

3~ How large is the tank? How long has the tank been set up?
10 gallons - setup for ~2 years - planted for about ~1 year 6 months

4~What type of filtration are you using? Please give the name and number (i.e. Fluval 304) and amount of gph if known.
HOB old school tetra not sure GPH + sponge filter

5~How many fish are in the tank? What kinds of fish are they and what are their current sizes?
7 lambchop raspboras - medium to larger sized | 2 virginae cory's (full sized?) | 2 banjo catfish (1 smaller male - 1 larger female) | ~12 amano shrimp

6~When is the last time you did a water change and vacuum the gravel? How often do you do this? How much water do you remove at a time?
Water changes are infrequent as numbers stay steady maybe once per month | its sanded so no gravel vaccing (banjo's disturb sand and filters pick up crap) | maybe 5 gallons

7~How long have you had the fish? If the fish is new, how did you acclimate it/them?
The lambchop in question I have either had since the tank started or he was bought as part of the expansion of their school so older than a year or so

8~Have you added anything new to the tank--decor, new dechlorinator, new substrate, etc.?
Nope

9~What kind of food have you been feeding your fish, have you changed their diet recently?
They get Xtreme aquatic nano food and whatever bits of the sinking pellets that the amanos shred into the water

Thanks for any advice in advance

 

[Andy Sager]

Most likely the fish had an internal issue which caused it to lose it's color and eventually die. Unfortunately, it's hard to tell the age of farmed fish because fish are sold by size, not by age so a stunted fish could be sold as a small when it should be the size of a large for it's age. It's very common for runts to be part of every spawn. Because it happened to only one fish and not the rest of the school, it's highly unlikely that it's a tank issue and so it's an individual issue. Organ damage can cause color loss as can vitamin deficiency. Because the other fish didn't show similar signs, organ damage is the most likely cause. That said, you change water for more reasons than just to reduce nitrates so not changing water allows the vitamins and minerals in the water to be absorbed by the fish which can also stunt their growth. You say the test results are " steady" but in reality, they aren't. Some aspects of the water are always changing. This is why routine water changes are recommended. Because you have the shrimp, you don't want to do large volume water changes so a change of 10% once or twice a week would be all I would do. Shrimp do not like drastic changes in their water parameters.
The potential cure would have needed to be done when the fish first showed the signs of losing it's color so at this point, unless other fish are showing similar signs, I would do nothing. If other fish were losing color, you would need to remove the fish to a hospital tank to treat with an antibiotic and vitamins.