i agree 86 in ocean is different thank a tank. with heat u get low oxygen levels.
No, any detrimental effect of temperature on our livestock is very unlikely to have anything to do with O2. At sea level, with natural salinty (35ppt), at 87 degrees F the O2 saturation level is about 6.18 mg/l. For reference, at 78F, it would be about 6.71 mg/l. So, this is about an 8% drop, however, from what I can find, generally anything over 5 mg/l is considered acceptable. So, this is well into the typically accepted safe zone. I.e. O2 has nothing to do directly, with any negative effects of temperature in our systems. Perhaps if there is high ammonia or some other stressor, the drop in O2 could be an added stressor, which could exacerbate the situation, but should not be a problem for a healthy tank.
What I think your saying however is that a tank is different from the ocean because the lack of O2 exchange in a closed system reduces the O2 level further. However, this does not seem to make sense. The temperature effects the saturation point of O2. The ability of gases to exchange between the air and water is going to be determined by barometric pressure and surface area. Temperature is not changing either of these parameters to any significant extent.
So, temperature is only effecting the waters O2 level if there is sufficient gas exchange to saturate the water. So, if your saying that the O2 level is reduced due to gas exchange limitations, then the O2 level isn't effected by the temperature. At least as long as the O2 saturation point of the water is higher than the O2 level which the gas exchange and barometric pressure is allowing. So, if O2 levels are an issue, it's due to gas exchange and has nothing to do with temperature, unless there is sufficient gas exchange to saturate. In this case however, the O2 will only be an issue if there is very, very high temperature (i.e. to get down to 5mg/l you need to be well above 100 degrees F), or there are other stressors which may exacerbate the situation.
So, in short, temperature does not have a significant effect on O2 in our systems. If it does, you have other, bigger issues. Temperature effects our livestock mainly because is interferes with protein function and causes biological mechanisms to function poorly or incorrectly. It is unlikely to have anything to do with O2.
Whether or not 87degerees effects your livestock will depend on the tolerated temperature range for a given organism and the acclimated range. From what you are describing, with the natural temp range of your tank, it sounds like 87, for a short time anyways, shouldn't be an issue.